Company lists · Data refreshed September 2026
Top 25 Security audit firms based in the United Kingdom
RevenueBase identified 465 security audit firms headquartered in the United Kingdom as of September 2026 and tracks 4,967 professional contacts across them, including 1,349 with verified work emails and 305 with mobile numbers. London is the largest hub.
This list covers security audit firms 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, how directly it supports the match, and when it was last checked. Data refreshed September 6, 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 security audit firms based in the United Kingdom
Ranked by team size| # | Company | Contacts | |||
|---|---|---|---|---|---|
| 1 | 705 | ||||
“Get a free, powerful security assessment with personalised recommendations, the same analysis that costs from IT Consultancies.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 2 | 242 | ||||
“Obrela Security Industries is a global provider of cyber security services.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 3 | 159 | ||||
“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: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 4 | 123 | ||||
“Bulletproof is now part of WorkNest Secure.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 5 | 80 | ||||
“At Reliance Cyber, we believe in truly partnering with our customers.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 6 | 74 | ||||
“Saepio increase awareness, reduce risk and improve security in a continually evolving threat landscape.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 7 | 73 | ||||
“Dionach by Nomios has over 25 years of expertise in information security, supporting organisations in building resilience against ever‑evolving cyber threats.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 8 | 60 | ||||
“Many organisations are dealing with multiple frameworks, overlapping tools, disconnected ownership, and increasing pressure from regulators, customers, and boards.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 9 | 57 | ||||
“CyberLab is the UK-leading cyber security consultancy and managed services provider, trusted by over 1,200 enterprise businesses, government departments, and household names to…” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 10 | 52 | ||||
“At Hexegic we are not just passionate about protecting data through our Cyber services we are passionate about helping companies release the potential of the data they hold…” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 11 | Purecyber LimitedPartial evidence | 49 | |||
“PureCyber is an award-winning, expert Cyber Security Consultancy.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 12 | 39 | ||||
“We help organisations understand, optimise, and strengthen their cybersecurity.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 13 | 38 | ||||
“Mitigo Group keeps professional services firms safe from cyberattack and operationally resilient.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 14 | 36 | ||||
“Secarma exists to keep the world safe.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 15 | Ergos UKIndirect evidence | 35 | |||
“ERGOS is an award-winning IT Managed Service Provider.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 16 | 32 | ||||
“Defense.com is transforming the way businesses manage cyber security by allowing them to easily identify, prioritise and remediate threats.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 17 | 32 | ||||
“Aristi is a specialist provider of cyber security services with over 17 years of experience.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 18 | 31 | ||||
“SPECIALISTS IN IT SECURITY AND COMPLIANCE Our goal is to help customers define, develop and implement information security and compliance services, no matter what stage of the…” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 19 | 31 | ||||
“Salus is a provider of world-class cyber security services, enabling our clients to identify and manage their cyber risks proactively and effectively.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 20 | 30 | ||||
“Cyber security can feel overwhelming.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 21 | 29 | ||||
“Imagine a world where cyber threats are simply another challenge that you're fully equipped to handle.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 22 | 26 | ||||
“Based in Manchester UK, we are an independent Cyber Security Consultancy providing Security services across a wide range of markets, from multi-national Corporate Organisations…” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 23 | 24 | ||||
“Whatever you supply, design, build, manufacture, or grow, its excelling at it that has got your business to where it is today.” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 24 | 23 | ||||
“CyberCrowd are a market leader in the cyber security realm, offering everything from Assessment Services through to Pen Testing, CISOaaS, Certification Readiness, DPO services…” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
| 25 | 23 | ||||
“AMR CyberSecurity delivers next generation cyber security services to assist organisations across a wide variety of sectors in understanding potential threats and effectively…” Source: company website · checked Sep 6, 2026Thanks. The Data Team will review it. | |||||
Showing 25 of 465 security audit firms based in the United Kingdom
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Security audit firms based in the United Kingdom at a glance
As of Sep 6, 2026Companies by employee count
Verified emails by last verification
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 security audit firms, so some rows will be adjacent to the category rather than pure plays. The description and evidence 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 SmartSearch, 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 “security audit firms”. Matching reads each company's description, not its industry code or its name.
- What we exclude
- Companies whose own description does not clearly place them among security audit firms, 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 an evidence 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, 1,349 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 6, 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.
Security audit firms by metro
- Security audit firms in London163
Frequently asked
How many security audit firms are there based in the United Kingdom?
RevenueBase identified 465 security audit firms 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?
COBRA, headquartered in London, tops this list with the largest team on record.
Which city has the most security audit firms?
London leads with 163 headquartered companies, followed by Manchester (22) and Birmingham (13).
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 1,349 verified decision-maker contacts tracked across these 465 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 6, 2026.
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Security audit firms by geography
- Security audit firms based in the United States
- Security audit firms based in France
- Security audit firms based in Canada
- Security audit firms based in Germany
- Security audit firms based in Brazil
- Security audit firms based in Australia
- Security audit firms based in the Netherlands
- Security audit firms based in Spain
- Security audit firms based in Poland
- Security audit firms based in South Africa
- Security audit firms based in Switzerland
- Security audit firms based in Italy
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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.