Company lists · Data refreshed November 2026

Top 21 Critical infrastructure security services based in the United Kingdom

RevenueBase identified 1,487 company matches for critical infrastructure security services associated with the United Kingdom as of November 2026 and tracks 30,979 professional contacts across them, including 7,145 with verified work emails. London is the largest hub.

This list covers company matches for critical infrastructure security services 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 November 5, 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.

How to read this list RevenueBase SmartSearch · Exact Recorded Nov 5, 2026 How this list was built
1,487Companies
30,979Contacts tracked
7,145Verified emails
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The 21 largest critical infrastructure security services based in the United Kingdom

Ranked by team size
Top 21 of 1,487 company matches for critical infrastructure security services based in the United Kingdom, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Nov 5, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#CompanyRevenueBase SmartSearchHeadquartersEmployeesContacts
1Exact matchWarwick, United KingdomHQ recorded Nov 5, 20261,001-5,0002,547 contacts →

Exact match

“Telent designs, builds, manages, and maintains the nation’s critical infrastructure technology that keeps the country moving, connected, and safe.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
2Exact matchNorthampton, United KingdomHQ recorded Nov 5, 202610001+1,667 contacts →

Exact match

“We are an intelligence-led security business.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
3Exact matchLondon, United KingdomHQ recorded Nov 5, 20261,001-5,0001,029 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 · Nov 5, 2026 · View company records in RevenueBase
4Exact matchLondon, United KingdomHQ recorded Nov 5, 20261,001-5,000458 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 · Nov 5, 2026 · View company records in RevenueBase
5Exact matchCirencester, United KingdomHQ recorded Nov 5, 20261,001-5,000449 contacts →

Exact match

“Unlike traditional security providers, we're redefining what protection means in today's world.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
6Exact matchBraintree, United KingdomHQ recorded Nov 5, 20261,001-5,000337 contacts →

Exact match

“Established in 1993, with commitment to our customers and staff alongside a strong ethos and standards driven approach, Regency Security is now the largest provider of door…”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
7Exact matchReading, United KingdomHQ recorded Nov 5, 2026201-500327 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 · Nov 5, 2026 · View company records in RevenueBase
8Exact matchHarlow, United KingdomHQ recorded Nov 5, 20261,001-5,000284 contacts →

Exact match

“SES Group was founded in 1998 by Dr Tony Ball and rebranded as SES Group in 2014.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
9Exact matchBarrow-upon-humber, United KingdomHQ recorded Nov 5, 20261,001-5,000275 contacts →

Exact match

“We have moved as Profile Security Services is now Proudly OCS.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
10Exact matchLeeds, United KingdomHQ recorded Nov 5, 2026501-1,000265 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 · Nov 5, 2026 · View company records in RevenueBase
11Exact matchGreenham, United KingdomHQ recorded Nov 5, 2026201-500256 contacts →

Exact match

“Roc Technologies delivers transformational IT solutions to public and private sector organisations across the UK.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
12Exact matchRomford, United KingdomHQ recorded Nov 5, 2026201-500203 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 · Nov 5, 2026 · View company records in RevenueBase
13Exact matchWoking, United KingdomHQ recorded Nov 5, 2026201-500202 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 · Nov 5, 2026 · View company records in RevenueBase
14Exact matchNewcastle Upon Tyne, United KingdomHQ recorded Nov 5, 202651-200187 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 · Nov 5, 2026 · View company records in RevenueBase
15Exact matchLeeds, United KingdomHQ recorded Nov 5, 20261,001-5,000184 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 · Nov 5, 2026 · View company records in RevenueBase
16Exact matchAlton, United KingdomHQ recorded Nov 5, 2026201-500181 contacts →

Exact match

“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…”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
17Exact matchEnfield, United KingdomHQ recorded Nov 5, 2026501-1,000171 contacts →

Exact match

“We are GUK.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
18Exact matchLondon, United KingdomHQ recorded Nov 5, 202651-200165 contacts →

Exact match

“The Keyholding Company are a tech-enabled mobile security services company, specialising in alarm response, mobile patrols, locks and unlocks, emergency and temporary guarding…”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
19Exact matchBradley Stoke, United KingdomHQ recorded Nov 5, 2026201-500164 contacts →

Exact match

“Logiq is a UK-based cyber security consultancy and secure managed services provider supporting defence, government, and critical national infrastructure (CNI) organisations where…”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
20Exact matchThatcham, United KingdomHQ recorded Nov 5, 202651-200161 contacts →

Exact match

“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…”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase
21Exact matchNewton-le-willows, United KingdomHQ recorded Nov 5, 20265,001-10,000151 contacts →

Exact match

“About Kingdom Security Established in March 1993, Kingdom Security is a leading UK security provider delivering professional, fully licensed security services nationwide.”

Recorded in the RevenueBase company graph · Nov 5, 2026 · View company records in RevenueBase

Showing 21 of 1,487 critical infrastructure security services based in the United Kingdom

See the full list, filter by size, metro and specialty, and access 7,145 tracked professional contacts with verified work emails. Direct dials are available where recorded.

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Critical infrastructure security services based in the United Kingdom at a glance

As of Nov 5, 2026
23.1%Verified-email coverage
20.8Average contacts per company
11-50Median size (employees)
33.7%Largest-city concentration · London
Nov 5, 2026Page data refreshed

Companies by employee count

1-10
651
11-50
453
51-200
240
201-500
80
501-1,000
23
1,001-5,000
16
5,001-10,000
2
10001+
5

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 1,487 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 security services” 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 7,145 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 November 5, 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.

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 security services”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many critical infrastructure security services are there based in the United Kingdom?

RevenueBase identified 1,487 company matches for critical infrastructure security services associated with the United Kingdom as of November 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?

Telent Technology Services LTD tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city has the most critical infrastructure security services?

London leads with 501 company records, followed by Manchester (42) and Birmingham (39).

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 7,145 professional contacts with verified work emails tracked across these 1,487 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 November 5, 2026.

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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 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.