Company lists · Data refreshed September 2026
Top 25 Critical infrastructure defense based in the United Kingdom
RevenueBase identified 1,678 company matches for critical infrastructure defense associated with the United Kingdom as of September 2026 and tracks 114,619 professional contacts across them, including 10,570 with verified work emails. London is the largest hub.
This list covers company matches for critical infrastructure defense associated with the United Kingdom, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed September 16, 2026.
Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.
The 25 largest critical infrastructure defense based in the United Kingdom
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 79,699 contacts → | ||||
Exact match “G4S is a leading security and facility services company that provides proactive security services and cutting-edge smart technology to deliver tailored, integrated security…” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 2 | 4,925 contacts → | ||||
Exact match “Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 3 | 1,508 contacts → | ||||
Exact match “We are an intelligence-led security business.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 4 | 919 contacts → | ||||
Exact match “CIS Security is an independent security company equipped to help customers to solve the complex challenges in today’s digital, connected and regulated business world.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 5 | 764 contacts → | ||||
Exact match “MTI provides award-winning, end-to-end technology solutions and services in cyber security and data centre for over 35 years.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 6 | 679 contacts → | ||||
Exact match “At Roke, we stand at the forefront of defence and security, delivering cutting-edge intelligence and engineering solutions that protect nations, troops, borders, and businesses.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 7 | 597 contacts → | ||||
Exact match “Part of ICTS Europe Group, ICTS UK & Ireland is a professional services firm which has been specialised in security risk for the past 39+ years.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 8 | 502 contacts → | ||||
Exact match “SecurityHQ, a global cybersecurity company pioneering Security Performance Engineering for stronger operational performance and resilience.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 9 | 422 contacts → | ||||
Exact match “Unlike traditional security providers, we're redefining what protection means in today's world.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 10 | 419 contacts → | ||||
Exact match “Ward is an award winning, privately owned business, providing bespoke risk and security solutions including protective security personnel, explosive search dogs, narcotic search…” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 11 | 358 contacts → | ||||
Exact match “ASEL design, develop and deliver fully bespoke and integrated security solutions, seamlessly bringing together people, technology and processes to achieve results-driven outcomes.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 12 | 303 contacts → | ||||
Exact match “Bridewell is the trusted cyber security partner for organisations operating within Critical National Infrastructure (CNI), as well as companies who want the highest standard of…” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 13 | 297 contacts → | ||||
Exact match “At Quorum Cyber, we're on a mission to help good people win.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 14 | 246 contacts → | ||||
Exact match “First Response Group (FRG) is one of the leading security, risk and FM providers in the UK delivering manned security, technology solutions, building management and vacant…” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 15 | 243 contacts → | ||||
Exact match “Roc Technologies delivers transformational IT solutions to public and private sector organisations across the UK.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 16 | 242 contacts → | ||||
Exact match “Obrela Security Industries is a global provider of cyber security services.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 17 | 205 contacts → | ||||
Exact match “Pilgrims are a global security, risk management and service support company that identifies and manages risks for clients across all sectors, including oil & gas, telecoms…” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 18 | 200 contacts → | ||||
Exact match “OpenView Security Solutions is the UK’S largest privately owned independent security company and provides unique, innovative and technologically excellent solutions to meet…” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 19 | 180 contacts → | ||||
Exact match “Established in 1978, Bridgegate Security is proud to be one of the UK’s largest independent security contractors.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 20 | 177 contacts → | ||||
Exact match “Whether you’re a business or an individual, digital threats to your precious data and assets can come in any form - external or internal.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 21 | 170 contacts → | ||||
Exact match “DeterTech is an industry leading provider of highly innovative and intelligence-led end-to-end security solutions.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 22 | 170 contacts → | ||||
Exact match “Looking after the things people care about, wherever they are’.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 23 | 168 contacts → | ||||
Exact match “Sapphire delivers comprehensive cyber solutions tailored to your needs, spanning across consultancy, managed services, IT/OT and beyond.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 24 | 166 contacts → | ||||
Exact match “We are GUK.” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
| 25 | 166 contacts → | ||||
Exact match “Providing Exceptional Security Services to Corporate and Retail Customers - Brooknight Security, with over 30 years of experience, is the go-to choice for businesses seeking…” Recorded in the RevenueBase company graph · Sep 16, 2026 · View company records in RevenueBase | |||||
RevenueBase SmartSearch
Describe a niche business in your own words. RevenueBase SmartSearch compares the meaning of your description with company business descriptions compiled in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit.
This list uses Exact for “critical infrastructure defense”. Each Exact match badge shows membership in that saved search; it is not an individual similarity score or a service-quality rating. Recorded descriptions are shown where available.
Showing 25 of 1,678 critical infrastructure defense based in the United Kingdom
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Critical infrastructure defense based in the United Kingdom at a glance
As of Sep 16, 2026Companies by employee count
Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 1,678 companies.
How this list was built
The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.
- Source
- The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
- What qualifies
- Company records associated with the United Kingdom whose business descriptions match “critical infrastructure defense” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
- RevenueBase SmartSearch
- Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
- Public preview
- The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
- Match quality
- RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
- Ranking
- Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
- Verification
- Every displayed company carries at least one verified work email. RevenueBase tracks 10,570 professional contacts with verified work emails across the full matched dataset. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
- Refresh
- This page's figures were pulled from the company graph on September 16, 2026. Lists refresh periodically as the graph is re-checked.
- Record context
- Company records and descriptions can change. Check the company's website for its current services and locations.
Critical infrastructure defense by metro
Frequently asked
What is RevenueBase SmartSearch?
RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “critical infrastructure defense”; each Exact match badge shows search membership, not an individual similarity or quality score.
How many critical infrastructure defense are there based in the United Kingdom?
RevenueBase identified 1,678 company matches for critical infrastructure defense associated with the United Kingdom as of September 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.
What is the largest company on this list?
G4s tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.
Which city has the most critical infrastructure defense?
London leads with 555 company records, followed by Manchester (49) and Birmingham (36).
How do I get contact information for these companies?
A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 10,570 professional contacts with verified work emails tracked across these 1,678 companies; direct dials are available where recorded.
How current is this list?
The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 16, 2026.
Ready to reach these companies? Verified emails and direct dials for all 1,678 critical infrastructure defense based in the United Kingdom. Start with a free account, no credit card.
Download this list →Related lists
Critical infrastructure defense by geography
- Critical infrastructure defense based in Adelaide, Australia
- Critical infrastructure defense based in Brisbane, Australia
- Critical infrastructure defense based in Canberra, Australia
- Critical infrastructure defense based in Melbourne, Australia
- Critical infrastructure defense based in Perth, Australia
- Critical infrastructure defense based in Sydney, Australia
- Critical infrastructure defense based in Belo Horizonte, Brazil
- Critical infrastructure defense based in Brasilia, Brazil
- Critical infrastructure defense based in Curitiba, Brazil
- Critical infrastructure defense based in Porto Alegre, Brazil
- Critical infrastructure defense based in Rio De Janeiro, Brazil
- Critical infrastructure defense based in Sao Paulo, Brazil
About this data
RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase SmartSearch, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.
More company lists
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- New lists
- Critical infrastructure defense based in Adelaide, Australia
- Critical infrastructure defense based in Brisbane, Australia
- Critical infrastructure defense based in Canberra, Australia
- Critical infrastructure defense based in Melbourne, Australia
- Critical infrastructure defense based in Perth, Australia
- Critical infrastructure defense based in Sydney, Australia
Company intelligence · public preview
Top 25 critical infrastructure defense based in the United Kingdom
Find companies in any niche.
Describe the businesses you want in your own words. RevenueBase SmartSearch matches company descriptions by meaning.
RevenueBase records 1,678 matching company records for critical infrastructure defense based in the United Kingdom, with 114,619 tracked contacts and 10,570 verified work emails.
This public preview shows 25 selected records ordered by tracked contacts. RevenueBase SmartSearch finds company descriptions that match by meaning at Exact. Snapshot: September 16, 2026.
RevenueBase compiles business descriptions for niche-company discovery; each row shows a recorded excerpt where available. Adapt this search to find the companies and contacts you want.
Top 25 critical infrastructure defense based in the United Kingdom
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
| # | Company | Headquarters on record | Reported employees | RevenueBase SmartSearch | Tracked contacts |
|---|---|---|---|---|---|
| 1 |  G4sg4s.comHQ: London, United KingdomReported employees: 10001+ | London, United Kingdom | 10001+ | Exact match | 79,699 contacts → |
“G4S is a leading security and facility services company that provides proactive security services and cutting-edge smart technology to deliver tailored, integrated security…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 2 |  Sophossophos.comHQ: Abingdon, United KingdomReported employees: 5,001-10,000 | Abingdon, United Kingdom | 5,001-10,000 | Exact match | 4,925 contacts → |
“Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 3 |  Mitie Securitymitie.comHQ: Northampton, United KingdomReported employees: 10001+ | Northampton, United Kingdom | 10001+ | Exact match | 1,508 contacts → |
“We are an intelligence-led security business.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 4 |  CIS Security Limitedcis-security.co.ukHQ: London, United KingdomReported employees: 1,001-5,000 | London, United Kingdom | 1,001-5,000 | Exact match | 919 contacts → |
“CIS Security is an independent security company equipped to help customers to solve the complex challenges in today’s digital, connected and regulated business world.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 5 |  MTImti.comHQ: Staines-upon-thames, United KingdomReported employees: 201-500 | Staines-upon-thames, United Kingdom | 201-500 | Exact match | 764 contacts → |
“MTI provides award-winning, end-to-end technology solutions and services in cyber security and data centre for over 35 years.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 6 |  ROKEroke.co.ukHQ: Romsey, United KingdomReported employees: 1,001-5,000 | Romsey, United Kingdom | 1,001-5,000 | Exact match | 679 contacts → |
“At Roke, we stand at the forefront of defence and security, delivering cutting-edge intelligence and engineering solutions that protect nations, troops, borders, and businesses.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 7 |  Icts UK & Irelandicts.co.ukHQ: London, United KingdomReported employees: 1,001-5,000 | London, United Kingdom | 1,001-5,000 | Exact match | 597 contacts → |
“Part of ICTS Europe Group, ICTS UK & Ireland is a professional services firm which has been specialised in security risk for the past 39+ years.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 8 |  Securityhqsecurityhq.comHQ: London, United KingdomReported employees: 501-1,000 | London, United Kingdom | 501-1,000 | Exact match | 502 contacts → |
“SecurityHQ, a global cybersecurity company pioneering Security Performance Engineering for stronger operational performance and resilience.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 9 |  Lodge Securitylodge-security.comHQ: Cirencester, United KingdomReported employees: 1,001-5,000 | Cirencester, United Kingdom | 1,001-5,000 | Exact match | 422 contacts → |
“Unlike traditional security providers, we're redefining what protection means in today's world.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 10 |  Ward Securityward-security.co.ukHQ: London, United KingdomReported employees: 1,001-5,000 | London, United Kingdom | 1,001-5,000 | Exact match | 419 contacts → |
“Ward is an award winning, privately owned business, providing bespoke risk and security solutions including protective security personnel, explosive search dogs, narcotic search…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 11 | HQ: London, United KingdomReported employees: 5,001-10,000 | London, United Kingdom | 5,001-10,000 | Exact match | 358 contacts → |
“ASEL design, develop and deliver fully bespoke and integrated security solutions, seamlessly bringing together people, technology and processes to achieve results-driven outcomes.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 12 |  Bridewellbridewell.comHQ: Reading, United KingdomReported employees: 201-500 | Reading, United Kingdom | 201-500 | Exact match | 303 contacts → |
“Bridewell is the trusted cyber security partner for organisations operating within Critical National Infrastructure (CNI), as well as companies who want the highest standard of…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 13 |  Quorum Cyberquorumcyber.comHQ: Edinburgh, United KingdomReported employees: 201-500 | Edinburgh, United Kingdom | 201-500 | Exact match | 297 contacts → |
“At Quorum Cyber, we're on a mission to help good people win.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 14 |  First Response Groupfirstresponsegroup.comHQ: Leeds, United KingdomReported employees: 501-1,000 | Leeds, United Kingdom | 501-1,000 | Exact match | 246 contacts → |
“First Response Group (FRG) is one of the leading security, risk and FM providers in the UK delivering manned security, technology solutions, building management and vacant…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 15 |  ROC Technologiesroctechnologies.comHQ: Greenham, United KingdomReported employees: 201-500 | Greenham, United Kingdom | 201-500 | Exact match | 243 contacts → |
“Roc Technologies delivers transformational IT solutions to public and private sector organisations across the UK.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 16 |  Obrelaobrela.comHQ: London, United KingdomReported employees: 201-500 | London, United Kingdom | 201-500 | Exact match | 242 contacts → |
“Obrela Security Industries is a global provider of cyber security services.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 17 |  Pilgrims Risk Management Grouppilgrims-rmg.comHQ: Woking, United KingdomReported employees: 201-500 | Woking, United Kingdom | 201-500 | Exact match | 205 contacts → |
“Pilgrims are a global security, risk management and service support company that identifies and manages risks for clients across all sectors, including oil & gas, telecoms…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 18 |  Openview Security Solutions Limitedopenviewgroup.comHQ: Romford, United KingdomReported employees: 201-500 | Romford, United Kingdom | 201-500 | Exact match | 200 contacts → |
“OpenView Security Solutions is the UK’S largest privately owned independent security company and provides unique, innovative and technologically excellent solutions to meet…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 19 |  Bridgegate Security UK Limitedbridgegate-security.co.ukHQ: Leeds, United KingdomReported employees: 1,001-5,000 | Leeds, United Kingdom | 1,001-5,000 | Exact match | 180 contacts → |
“Established in 1978, Bridgegate Security is proud to be one of the UK’s largest independent security contractors.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 20 |  Deepcytes Cyber Labs UKdeepcytes.ioHQ: London, United KingdomReported employees: 51-200 | London, United Kingdom | 51-200 | Exact match | 177 contacts → |
“Whether you’re a business or an individual, digital threats to your precious data and assets can come in any form - external or internal.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 21 |  Detertech UKdetertech.comHQ: Telford, United KingdomReported employees: 51-200 | Telford, United Kingdom | 51-200 | Exact match | 170 contacts → |
“DeterTech is an industry leading provider of highly innovative and intelligence-led end-to-end security solutions.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 22 |  Texecom LTDtexe.comHQ: Haslingden, United KingdomReported employees: 201-500 | Haslingden, United Kingdom | 201-500 | Exact match | 170 contacts → |
“Looking after the things people care about, wherever they are’.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 23 |  Sapphiresapphire.netHQ: Newcastle Upon Tyne, United KingdomReported employees: 51-200 | Newcastle Upon Tyne, United Kingdom | 51-200 | Exact match | 168 contacts → |
“Sapphire delivers comprehensive cyber solutions tailored to your needs, spanning across consultancy, managed services, IT/OT and beyond.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 24 |  Guarding UKguk.co.ukHQ: Enfield, United KingdomReported employees: 501-1,000 | Enfield, United Kingdom | 501-1,000 | Exact match | 166 contacts → |
“We are GUK.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 25 |  The Brooknight Groupthebrooknightgroup.co.ukHQ: Milton Keynes, United KingdomReported employees: 201-500 | Milton Keynes, United Kingdom | 201-500 | Exact match | 166 contacts → |
“Providing Exceptional Security Services to Corporate and Retail Customers - Brooknight Security, with over 30 years of experience, is the go-to choice for businesses seeking…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
Showing 25 of 1,678 company matches
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Critical infrastructure defense: dataset insights
September 16, 2026These summaries describe recorded coverage in this saved dataset. This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Reported company sizes
1,672 records in the displayed employee bands.
6 matching records are outside the displayed bands or do not have a displayed size. Bars show shares of the displayed bands.
Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 1,678 companies.
How this company list was built
Describe a niche in your own words: companies installing commercial solar, or manufacturers of sustainable packaging. RevenueBase SmartSearch finds companies whose compiled business descriptions match by meaning. This list is one saved example to adapt.
Where the company descriptions come from
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
RevenueBase SmartSearch matching settings
- Exact
- Closest fits to the business described.
- Similar
- Similar businesses with a wider range of fits.
- Related
- Related businesses in and around the category.
- Broad
- A broader set of businesses connected to the description.
RevenueBase SmartSearch · Exact match identifies inclusion in this search's closest semantic matching setting. It is not a per-company confidence score, a literal keyword match, or a quality endorsement.
Selection, ordering and scope
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Recorded company descriptions support research; check company websites for current services. The selected preview is ordered by tracked contacts and is not a list of the best service providers.
Snapshot: September 16, 2026.
RevenueBase is a B2B data infrastructure company. Its September 3, 2026 published methodology describes a graph of 60 million companies and 398.9 million professional contacts; these platform figures differ from this page's totals. Published methodology ↗
Critical infrastructure defense by metro
Questions about this company list
What does Exact match mean for critical infrastructure defense?
The separate RevenueBase SmartSearch column identifies inclusion at the closest semantic matching preset. It is not a literal keyword match, a per-company confidence score or a quality endorsement. Changing the search form opens a new search in RevenueBase; it does not reclassify these saved rows.
How many critical infrastructure defense did RevenueBase find based in the United Kingdom?
The saved snapshot records 1,678 matching company records, 114,619 tracked contacts and 10,570 verified emails. The public preview displays 25 selected records.
Where do the company descriptions come from?
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
How are the public companies ordered?
The selected public records are ordered by contacts tracked in RevenueBase, highest first. Contact coverage is a prospecting measure, not an assessment of the company's services or quality.
How can I get contact information?
Select a company's contact count to open its filtered contacts in RevenueBase. Free signup is required and includes 500 credits and limited free results. Verified emails, direct dials and mobile numbers depend on available coverage.
How current is this list?
Snapshot: September 16, 2026. Review each company's website for current services and locations. A recorded business description does not establish that every company offers every service named in the search.
What do headquarters and employee bands mean?
These are recorded company-level fields, rather than a map of every branch or a count of specialists. Missing headquarters or employee bands are labeled; older records may show a location separately from recorded headquarters.
Build your next target company list
Adapt this niche search and work with available contacts in RevenueBase.
Related lists
Critical infrastructure defense by geography
- Critical infrastructure defense based in Adelaide, Australia
- Critical infrastructure defense based in Brisbane, Australia
- Critical infrastructure defense based in Canberra, Australia
- Critical infrastructure defense based in Melbourne, Australia
- Critical infrastructure defense based in Perth, Australia
- Critical infrastructure defense based in Sydney, Australia
- Critical infrastructure defense based in Belo Horizonte, Brazil
- Critical infrastructure defense based in Brasilia, Brazil
- Critical infrastructure defense based in Curitiba, Brazil
- Critical infrastructure defense based in Porto Alegre, Brazil
- Critical infrastructure defense based in Rio De Janeiro, Brazil
- Critical infrastructure defense based in Sao Paulo, Brazil
Cite this list
RevenueBase Data Team. Top 25 critical infrastructure defense based in the United Kingdom. Snapshot: September 16, 2026. https://revenuebase.ai/companies/critical-infrastructure-defense/united-kingdom.
This is a selected public preview of saved company records, rather than an independently verified census. Open the source page ↗
More company lists
- All company lists
- Lists by location
- Lists A-Z
- New lists
- Critical infrastructure defense based in Adelaide, Australia
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Company intelligence · public preview
Top 25 critical infrastructure defense based in the United Kingdom
RevenueBase records 1,678 matching company records for critical infrastructure defense based in the United Kingdom, with 114,619 tracked contacts and 10,570 verified work emails.
This public preview shows 25 selected records ordered by tracked contacts. RevenueBase SmartSearch finds company descriptions that match by meaning at Exact. Snapshot: September 16, 2026.
RevenueBase compiles business descriptions for niche-company discovery; each row shows a recorded excerpt where available. Adapt this search to find the companies and contacts you want.
Top 25 critical infrastructure defense based in the United Kingdom
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
| # | Company | Headquarters on record | Reported employees | RevenueBase SmartSearch | Tracked contacts |
|---|---|---|---|---|---|
| 1 | G4sg4s.com HQ: London, United KingdomReported employees: 10001+ | London, United Kingdom | 10001+ | Exact match | 79,699 contacts → |
“G4S is a leading security and facility services company that provides proactive security services and cutting-edge smart technology to deliver tailored, integrated security…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 2 | Sophossophos.com HQ: Abingdon, United KingdomReported employees: 5,001-10,000 | Abingdon, United Kingdom | 5,001-10,000 | Exact match | 4,925 contacts → |
“Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 3 | Mitie Securitymitie.com HQ: Northampton, United KingdomReported employees: 10001+ | Northampton, United Kingdom | 10001+ | Exact match | 1,508 contacts → |
“We are an intelligence-led security business.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 4 | CIS Security Limitedcis-security.co.uk HQ: London, United KingdomReported employees: 1,001-5,000 | London, United Kingdom | 1,001-5,000 | Exact match | 919 contacts → |
“CIS Security is an independent security company equipped to help customers to solve the complex challenges in today’s digital, connected and regulated business world.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 5 | MTImti.com HQ: Staines-upon-thames, United KingdomReported employees: 201-500 | Staines-upon-thames, United Kingdom | 201-500 | Exact match | 764 contacts → |
“MTI provides award-winning, end-to-end technology solutions and services in cyber security and data centre for over 35 years.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 6 | ROKEroke.co.uk HQ: Romsey, United KingdomReported employees: 1,001-5,000 | Romsey, United Kingdom | 1,001-5,000 | Exact match | 679 contacts → |
“At Roke, we stand at the forefront of defence and security, delivering cutting-edge intelligence and engineering solutions that protect nations, troops, borders, and businesses.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 7 | Icts UK & Irelandicts.co.uk HQ: London, United KingdomReported employees: 1,001-5,000 | London, United Kingdom | 1,001-5,000 | Exact match | 597 contacts → |
“Part of ICTS Europe Group, ICTS UK & Ireland is a professional services firm which has been specialised in security risk for the past 39+ years.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 8 | Securityhqsecurityhq.com HQ: London, United KingdomReported employees: 501-1,000 | London, United Kingdom | 501-1,000 | Exact match | 502 contacts → |
“SecurityHQ, a global cybersecurity company pioneering Security Performance Engineering for stronger operational performance and resilience.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 9 | Lodge Securitylodge-security.com HQ: Cirencester, United KingdomReported employees: 1,001-5,000 | Cirencester, United Kingdom | 1,001-5,000 | Exact match | 422 contacts → |
“Unlike traditional security providers, we're redefining what protection means in today's world.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 10 | Ward Securityward-security.co.uk HQ: London, United KingdomReported employees: 1,001-5,000 | London, United Kingdom | 1,001-5,000 | Exact match | 419 contacts → |
“Ward is an award winning, privately owned business, providing bespoke risk and security solutions including protective security personnel, explosive search dogs, narcotic search…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 11 | HQ: London, United KingdomReported employees: 5,001-10,000 | London, United Kingdom | 5,001-10,000 | Exact match | 358 contacts → |
“ASEL design, develop and deliver fully bespoke and integrated security solutions, seamlessly bringing together people, technology and processes to achieve results-driven outcomes.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 12 | Bridewellbridewell.com HQ: Reading, United KingdomReported employees: 201-500 | Reading, United Kingdom | 201-500 | Exact match | 303 contacts → |
“Bridewell is the trusted cyber security partner for organisations operating within Critical National Infrastructure (CNI), as well as companies who want the highest standard of…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 13 | Quorum Cyberquorumcyber.com HQ: Edinburgh, United KingdomReported employees: 201-500 | Edinburgh, United Kingdom | 201-500 | Exact match | 297 contacts → |
“At Quorum Cyber, we're on a mission to help good people win.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 14 | First Response Groupfirstresponsegroup.com HQ: Leeds, United KingdomReported employees: 501-1,000 | Leeds, United Kingdom | 501-1,000 | Exact match | 246 contacts → |
“First Response Group (FRG) is one of the leading security, risk and FM providers in the UK delivering manned security, technology solutions, building management and vacant…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 15 | ROC Technologiesroctechnologies.com HQ: Greenham, United KingdomReported employees: 201-500 | Greenham, United Kingdom | 201-500 | Exact match | 243 contacts → |
“Roc Technologies delivers transformational IT solutions to public and private sector organisations across the UK.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 16 | Obrelaobrela.com HQ: London, United KingdomReported employees: 201-500 | London, United Kingdom | 201-500 | Exact match | 242 contacts → |
“Obrela Security Industries is a global provider of cyber security services.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 17 | Pilgrims Risk Management Grouppilgrims-rmg.com HQ: Woking, United KingdomReported employees: 201-500 | Woking, United Kingdom | 201-500 | Exact match | 205 contacts → |
“Pilgrims are a global security, risk management and service support company that identifies and manages risks for clients across all sectors, including oil & gas, telecoms…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 18 | Openview Security Solutions Limitedopenviewgroup.com HQ: Romford, United KingdomReported employees: 201-500 | Romford, United Kingdom | 201-500 | Exact match | 200 contacts → |
“OpenView Security Solutions is the UK’S largest privately owned independent security company and provides unique, innovative and technologically excellent solutions to meet…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 19 | Bridgegate Security UK Limitedbridgegate-security.co.uk HQ: Leeds, United KingdomReported employees: 1,001-5,000 | Leeds, United Kingdom | 1,001-5,000 | Exact match | 180 contacts → |
“Established in 1978, Bridgegate Security is proud to be one of the UK’s largest independent security contractors.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 20 | Deepcytes Cyber Labs UKdeepcytes.io HQ: London, United KingdomReported employees: 51-200 | London, United Kingdom | 51-200 | Exact match | 177 contacts → |
“Whether you’re a business or an individual, digital threats to your precious data and assets can come in any form - external or internal.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 21 | Detertech UKdetertech.com HQ: Telford, United KingdomReported employees: 51-200 | Telford, United Kingdom | 51-200 | Exact match | 170 contacts → |
“DeterTech is an industry leading provider of highly innovative and intelligence-led end-to-end security solutions.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 22 | Texecom LTDtexe.com HQ: Haslingden, United KingdomReported employees: 201-500 | Haslingden, United Kingdom | 201-500 | Exact match | 170 contacts → |
“Looking after the things people care about, wherever they are’.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 23 | Sapphiresapphire.net HQ: Newcastle Upon Tyne, United KingdomReported employees: 51-200 | Newcastle Upon Tyne, United Kingdom | 51-200 | Exact match | 168 contacts → |
“Sapphire delivers comprehensive cyber solutions tailored to your needs, spanning across consultancy, managed services, IT/OT and beyond.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 24 | Guarding UKguk.co.uk HQ: Enfield, United KingdomReported employees: 501-1,000 | Enfield, United Kingdom | 501-1,000 | Exact match | 166 contacts → |
“We are GUK.” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
| 25 | The Brooknight Groupthebrooknightgroup.co.uk HQ: Milton Keynes, United KingdomReported employees: 201-500 | Milton Keynes, United Kingdom | 201-500 | Exact match | 166 contacts → |
“Providing Exceptional Security Services to Corporate and Retail Customers - Brooknight Security, with over 30 years of experience, is the go-to choice for businesses seeking…” Recorded description excerpt · September 16, 2026Open company data in RevenueBase ↗Free signup required. | |||||
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Critical infrastructure defense: dataset insights
September 16, 2026These summaries describe recorded coverage in this saved dataset. This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Reported company sizes
1,672 records in the displayed employee bands.
6 matching records are outside the displayed bands or do not have a displayed size. Bars show shares of the displayed bands.
Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 1,678 companies.
How this company list was built
Describe a niche in your own words: companies installing commercial solar, or manufacturers of sustainable packaging. RevenueBase SmartSearch finds companies whose compiled business descriptions match by meaning. This list is one saved example to adapt.
Where the company descriptions come from
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
RevenueBase SmartSearch matching settings
- Exact
- Closest fits to the business described.
- Similar
- Similar businesses with a wider range of fits.
- Related
- Related businesses in and around the category.
- Broad
- A broader set of businesses connected to the description.
RevenueBase SmartSearch · Exact match identifies inclusion in this search's closest semantic matching setting. It is not a per-company confidence score, a literal keyword match, or a quality endorsement.
Selection, ordering and scope
The public list shows selected company records with contact and verified-email coverage. Reported employee bands provide separate company-size context.
This page is derived from saved source records; per-contact mobile coverage and email-recency results are not established by this snapshot.
Recorded company descriptions support research; check company websites for current services. The selected preview is ordered by tracked contacts and is not a list of the best service providers.
Snapshot: September 16, 2026.
RevenueBase is a B2B data infrastructure company. Its September 3, 2026 published methodology describes a graph of 60 million companies and 398.9 million professional contacts; these platform figures differ from this page's totals. Published methodology ↗
Critical infrastructure defense by metro
Questions about this company list
What does Exact match mean for critical infrastructure defense?
The separate RevenueBase SmartSearch column identifies inclusion at the closest semantic matching preset. It is not a literal keyword match, a per-company confidence score or a quality endorsement. Changing the search form opens a new search in RevenueBase; it does not reclassify these saved rows.
How many critical infrastructure defense did RevenueBase find based in the United Kingdom?
The saved snapshot records 1,678 matching company records, 114,619 tracked contacts and 10,570 verified emails. The public preview displays 25 selected records.
Where do the company descriptions come from?
RevenueBase compiles company information from public sources, including company websites and public professional profiles such as LinkedIn, alongside information supplied by companies. The short recorded excerpt shown here is separate from the complete business description used for matching; individual source URLs and collection dates are not provided in this public snapshot.
How are the public companies ordered?
The selected public records are ordered by contacts tracked in RevenueBase, highest first. Contact coverage is a prospecting measure, not an assessment of the company's services or quality.
How can I get contact information?
Select a company's contact count to open its filtered contacts in RevenueBase. Free signup is required and includes 500 credits and limited free results. Verified emails, direct dials and mobile numbers depend on available coverage.
How current is this list?
Snapshot: September 16, 2026. Review each company's website for current services and locations. A recorded business description does not establish that every company offers every service named in the search.
What do headquarters and employee bands mean?
These are recorded company-level fields, rather than a map of every branch or a count of specialists. Missing headquarters or employee bands are labeled; older records may show a location separately from recorded headquarters.
Build your next target company list
Adapt this niche search and work with available contacts in RevenueBase.
Related lists
Critical infrastructure defense by geography
- Critical infrastructure defense based in Adelaide, Australia
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- Critical infrastructure defense based in Canberra, Australia
- Critical infrastructure defense based in Melbourne, Australia
- Critical infrastructure defense based in Perth, Australia
- Critical infrastructure defense based in Sydney, Australia
- Critical infrastructure defense based in Belo Horizonte, Brazil
- Critical infrastructure defense based in Brasilia, Brazil
- Critical infrastructure defense based in Curitiba, Brazil
- Critical infrastructure defense based in Porto Alegre, Brazil
- Critical infrastructure defense based in Rio De Janeiro, Brazil
- Critical infrastructure defense based in Sao Paulo, Brazil
Cite this list
RevenueBase Data Team. Top 25 critical infrastructure defense based in the United Kingdom. Snapshot: September 16, 2026. https://revenuebase.ai/companies/critical-infrastructure-defense/united-kingdom.
This is a selected public preview of saved company records, rather than an independently verified census. Open the source page ↗
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- Critical infrastructure defense based in Adelaide, Australia
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