Company lists · Data refreshed September 2026

Top 25 IT security assessment firms based in the United Kingdom

RevenueBase identified 946 company matches for IT security assessment firms associated with the United Kingdom as of September 2026 and tracks 14,352 professional contacts across them, including 5,808 with verified work emails. London is the largest hub.

This list covers company matches for IT security assessment firms 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 28, 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 Sep 28, 2026 How this list was built
946Companies
14,352Contacts tracked
5,808Verified emails
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The 25 largest IT security assessment firms based in the United Kingdom

Ranked by team size
Top 25 of 946 company matches for IT security assessment firms based in the United Kingdom, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Sep 28, 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 matchAbingdon, United KingdomHQ recorded Sep 28, 20265,001-10,0004,925 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 28, 2026 · View company records in RevenueBase
2Exact matchLondon, United KingdomHQ recorded Sep 28, 2026n/a705 contacts →

Exact match

“Get a free, powerful security assessment with personalised recommendations, the same analysis that costs from IT Consultancies.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
3Exact matchLondon, United KingdomHQ recorded Sep 28, 2026501-1,000502 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 28, 2026 · View company records in RevenueBase
4Exact matchLondon, United KingdomHQ recorded Sep 28, 2026201-500242 contacts →

Exact match

“Obrela Security Industries is a global provider of cyber security services.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
5Exact matchThatcham, United KingdomHQ recorded Sep 28, 202651-200159 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 · Sep 28, 2026 · View company records in RevenueBase
6Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-200126 contacts →

Exact match

“We are TRPGLOBAL, your strategic partner in helping you with the complexities of risk management.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
7Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-200123 contacts →

Exact match

“Bulletproof is now part of WorkNest Secure.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
8Exact matchLeeds, United KingdomHQ recorded Sep 28, 202651-20099 contacts →

Exact match

“AppCheck is a Complete Enterprise Security Testing Solution that provides up to the minute vulnerability coverage for your entire estate.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
9Exact matchLondon, United KingdomHQ recorded Sep 28, 2026201-50097 contacts →

Exact match

“As an independent IT security specialist, Caretower provide comprehensive solutions to individual problems, thus allowing our recommendations to be unbiased.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
10Exact matchLeeds, United KingdomHQ recorded Sep 28, 202651-20090 contacts →

Exact match

“Solutions | Testing | Knowledge Helping You Protect Your Business From Cyber Attackers Your security and compliance partner, delivering trust worldwide Cognisys are your trusted…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
11Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-20087 contacts →

Exact match

“ITC Secure is an advisory-led cyber security services company.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
12Exact matchStourport-on-severn, United KingdomHQ recorded Sep 28, 2026201-50086 contacts →

Exact match

“CyberGuard Technologies is the security division of Wavenet.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
13Exact matchBasingstoke, United KingdomHQ recorded Sep 28, 202611-5085 contacts →

Exact match

“Amethyst Risk Management is a leading cybersecurity consultancy supplying expert services and support to the UK Government, Defence, Operators of Essential Services, and the…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
14Exact matchSwindon, United KingdomHQ recorded Sep 28, 202651-20080 contacts →

Exact match

“When your business relies on security, compliance and a strong reputation for taking care of your customers, you need a partner that understands your ethos, your challenges and…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
15Exact matchWaterloo, United KingdomHQ recorded Sep 28, 202651-20080 contacts →

Exact match

“At Reliance Cyber, we believe in truly partnering with our customers.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
16Exact matchHigh Wycombe, United KingdomHQ recorded Sep 28, 202651-20074 contacts →

Exact match

“Saepio increase awareness, reduce risk and improve security in a continually evolving threat landscape.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
17Exact matchOxford, United KingdomHQ recorded Sep 28, 202651-20073 contacts →

Exact match

“Dionach by Nomios has over 25 years of expertise in information security, supporting organisations in building resilience against ever‑evolving cyber threats.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
18Exact matchGloucester, United KingdomHQ recorded Sep 28, 202651-20069 contacts →

Exact match

“Modern cyber resilience demands more than isolated controls.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
19Exact matchBasingstoke, United KingdomHQ recorded Sep 28, 202651-20065 contacts →

Exact match

“We’re here to provide world-leading vulnerability research and capabilities!”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
20Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-20064 contacts →

Exact match

“YOU DESERVE TO BE HACKED®.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
21Exact matchDoncaster, United KingdomHQ recorded Sep 28, 202651-20062 contacts →

Exact match

“At DigitalXRAID, we’re more than just a managed security services provider – we’re your trusted partner in safeguarding your business from cyber threats.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
22Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-20062 contacts →

Exact match

“Cyro Cyber are your cyber security Guardians.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
23Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-20061 contacts →

Exact match

“Intruder's continuous exposure management platform helps security, IT, and engineering teams stop breaches before they start.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
24Exact matchMacclesfield, United KingdomHQ recorded Sep 28, 202611-5061 contacts →

Exact match

“MDSec are a UK based consultancy with a passion for information security.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
25Exact matchSouthampton, United KingdomHQ recorded Sep 28, 202651-20060 contacts →

Exact match

“Many organisations are dealing with multiple frameworks, overlapping tools, disconnected ownership, and increasing pressure from regulators, customers, and boards.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase

Showing 25 of 946 IT security assessment firms based in the United Kingdom

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IT security assessment firms based in the United Kingdom at a glance

As of Sep 28, 2026
40.5%Verified-email coverage
15.2Average contacts per company
1-10Median size (employees)
40.3%Largest-city concentration · London
Sep 28, 2026Page data refreshed

Companies by employee count

1-10
590
11-50
268
51-200
64
201-500
15
501-1,000
4
1,001-5,000
3
5,001-10,000
2

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 946 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 “IT security assessment firms” 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 5,808 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 28, 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 “IT security assessment firms”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many IT security assessment firms are there based in the United Kingdom?

RevenueBase identified 946 company matches for IT security assessment firms 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?

Sophos tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city has the most IT security assessment firms?

London leads with 381 company records, followed by Manchester (44) and Birmingham (22).

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 5,808 professional contacts with verified work emails tracked across these 946 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 28, 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.