Company lists · Data refreshed September 2026
Top 25 Critical infrastructure security companies based in the United Kingdom
RevenueBase identified 894 critical infrastructure security companies headquartered in the United Kingdom as of September 2026 and tracks 17,828 professional contacts across them, including 3,769 with verified work emails. London is the largest hub.
This list covers critical infrastructure security companies headquartered in the United Kingdom, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 27, 2026.
Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, 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 security companies based in the United Kingdom
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 919 contacts → | ||||
Partial evidence “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.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 2 | 597 contacts → | ||||
Partial evidence “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.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 3 | 502 contacts → | ||||
Partial evidence “SecurityHQ, a global cybersecurity company pioneering Security Performance Engineering for stronger operational performance and resilience.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 4 | 422 contacts → | ||||
Partial evidence “Unlike traditional security providers, we're redefining what protection means in today's world.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 5 | 303 contacts → | ||||
Strong evidence “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…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 6 | 242 contacts → | ||||
Partial evidence “Obrela Security Industries is a global provider of cyber security services.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 7 | 205 contacts → | ||||
Partial evidence “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…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 8 | 200 contacts → | ||||
Partial evidence “OpenView Security Solutions is the UK’S largest privately owned independent security company and provides unique, innovative and technologically excellent solutions to meet…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 9 | 180 contacts → | ||||
Partial evidence “Established in 1978, Bridgegate Security is proud to be one of the UK’s largest independent security contractors.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 10 | 168 contacts → | ||||
Indirect evidence “Sapphire delivers comprehensive cyber solutions tailored to your needs, spanning across consultancy, managed services, IT/OT and beyond.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 11 | 166 contacts → | ||||
Indirect evidence “We are GUK.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 12 | 166 contacts → | ||||
Partial evidence “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…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 13 | 165 contacts → | ||||
Partial evidence “Exclusive Networks is a global trusted cybersecurity specialist for digital infrastructure helping to drive the transition to a totally trusted digital future for all people and…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 14 | 165 contacts → | ||||
Strong evidence “Ovarro's technology is used throughout the world to monitor, control and manage critical and national infrastructure.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 15 | 159 contacts → | ||||
Strong evidence “At Cyberfort we are passionate about the cyber security services we deliver for our customers which keeps their people, data, systems and technology infrastructure secure…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 16 | 137 contacts → | ||||
Partial evidence “The Keyholding Company are a tech-enabled mobile security services company, specialising in alarm response, mobile patrols, locks and unlocks, emergency and temporary guarding…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 17 | 127 contacts → | ||||
Partial evidence “Vespasian Security was formed in February 2006.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 18 | 125 contacts → | ||||
Partial evidence “KHIPU Networks is an award winning international Cyber Security Company delivering a wide range of network, wireless and security solutions, technologies and services across…” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 19 | 115 contacts → | ||||
Indirect evidence “Solace Global Risk began in 2010 with a simple belief: when people face risk, they need partners who act quickly and stand by their word.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 20 | 106 contacts → | ||||
Indirect evidence “Protecting People, Property, Assets & Brands.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 21 | 105 contacts → | ||||
Indirect evidence “Cybersecurity specialists providing technology and telecoms solutions that gives you the leadership, experience and resilience you need to build and secure the future of work.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 22 | 95 contacts → | ||||
Partial evidence “Optilan is a leading independent security and communications systems integrator worldwide.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 23 | 93 contacts → | ||||
Indirect evidence “Innovation is at our core.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 24 | 91 contacts → | ||||
Partial evidence “Octavian Security is part of the Octavian Group, a global leader delivering integrated solutions across security, facilities management, and technology-led services.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
| 25 | 87 contacts → | ||||
Partial evidence “ITC Secure is an advisory-led cyber security services company.” Source: RevenueBase Database · checked Sep 27, 2026Thanks. The Data Team will review it. | |||||
RevenueBase Smart Search
RevenueBase Smart Search assesses information from a company’s LinkedIn profile, information supplied directly by the company, its website, and other publicly available sources. It uses that information to rate how closely the company relates to this list’s category: critical infrastructure security companies. Every row carries its rating and the description the rating was read from, so each one can be checked rather than taken on trust.
- Strong evidence
- The company's own public description of its business names critical infrastructure security companies.
- Partial evidence
- Its own public description names part of critical infrastructure security companies, so it works in or next to the category without describing itself that way.
- Indirect evidence
- The description shown does not name critical infrastructure security companies. The match rests on the rest of the company's public profile rather than the one sentence quoted here, so this is the rating to check first.
RevenueBase Smart Search is how these lists are built: RevenueBase's data engine and AI assemble the companies that match a category defined in a user's own words, so a list can be about what companies actually do rather than about whichever industry code they were filed under.
Showing 25 of 894 critical infrastructure security companies based in the United Kingdom
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Critical infrastructure security companies based in the United Kingdom at a glance
As of Sep 27, 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 894 companies.
How this list was built
Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among critical infrastructure security companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.
- Source
- The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
- What qualifies
- Companies headquartered in the United Kingdom whose own description of what they do matches “critical infrastructure security companies”. Matching reads each company's description, not its industry code or its name.
- RevenueBase Smart Search
- RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names critical infrastructure security companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
- What we exclude
- Companies whose own description does not clearly place them among critical infrastructure security companies, and records with no verified work email. Companies headquartered outside United Kingdom are excluded even when they keep an office there.
- Match quality
- In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
- 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 listed company carries at least one verified work email, 3,769 across the full list. 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 27, 2026. Lists refresh periodically as the graph is re-checked.
- Corrections
- Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.
Critical infrastructure security companies by metro
Frequently asked
What is RevenueBase Smart Search?
RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names critical infrastructure security companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.
How many critical infrastructure security companies are there based in the United Kingdom?
RevenueBase identified 894 critical infrastructure security companies headquartered in the United Kingdom as of September 2026, matched on each company's own description of what it does rather than its industry code.
What is the largest company on this list?
CIS Security Limited, headquartered in London, tops this list with the largest team on record.
Which city has the most critical infrastructure security companies?
London leads with 304 headquartered companies, followed by Manchester (26) and Birmingham (24).
How do I get contact information for these companies?
A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 3,769 verified decision-maker contacts tracked across these 894 companies.
How current is this list?
The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 27, 2026.
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Critical infrastructure security companies by geography
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- Critical infrastructure security companies based in Calgary, Canada
- Critical infrastructure security companies based in Montreal, Canada
- Critical infrastructure security companies based in Ottawa, Canada
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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 Smart Search, 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.
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