Company lists · Data refreshed September 2026

Top 25 Security consulting firms based in London, United Kingdom

Name: Security consulting firms based in London, United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 14, 2026 559 companies tracked

RevenueBase identified 559 security consulting firms headquartered in London, United Kingdom as of September 2026 and tracks 5,491 professional contacts across them, including 1,441 with verified work emails. London is the largest hub.

This list covers security consulting firms headquartered in London, 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 14, 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.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 14, 2026 86% judged on-target in blind review

559Companies

5,491Contacts tracked

1,441Verified emails

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The 25 largest security consulting firms based in London, United Kingdom

Ranked by team size

Top 25 of 559 security consulting firms based in London, United Kingdom, ranked by team size, largest first. Data refreshed Sep 14, 2026. RevenueBase Smart Search rates how each company's information relates to security consulting firms: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#	Company	RevenueBase Smart Search	Headquarters	Employees	Contacts
1	Argenbright Security Europe Limited - Asel	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	5,001-10,000	358 contacts →
	Partial evidence “ASEL design, develop and deliver fully bespoke and integrated security solutions, seamlessly bringing together people, technology and processes to achieve results-driven outcomes.” Source: RevenueBase Database · checked Sep 14, 2026
2	Obrela	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	201-500	242 contacts →
	Partial evidence “Obrela Security Industries is a global provider of cyber security services.” Source: RevenueBase Database · checked Sep 14, 2026
3	Turnkey Consulting	Strong evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	134 contacts →
	Strong evidence “Turnkey Consulting brings together people, protection, and performance to help the world’s leading companies understand and optimize their risk and security landscape.” Source: RevenueBase Database · checked Sep 14, 2026
4	Trpglobal	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	126 contacts →
	Indirect evidence “We are TRPGLOBAL, your strategic partner in helping you with the complexities of risk management.” Source: RevenueBase Database · checked Sep 14, 2026
5	Bulletproof Cyber Security	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	123 contacts →
	Indirect evidence “Bulletproof is now part of WorkNest Secure.” Source: RevenueBase Database · checked Sep 14, 2026
6	Caretower An Integrity360 Company	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	201-500	97 contacts →
	Partial evidence “As an independent IT security specialist, Caretower provide comprehensive solutions to individual problems, thus allowing our recommendations to be unbiased.” Source: RevenueBase Database · checked Sep 14, 2026
7	ITC Secure	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	87 contacts →
	Partial evidence “ITC Secure is an advisory-led cyber security services company.” Source: RevenueBase Database · checked Sep 14, 2026
8	ARK Workplace Risk	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	82 contacts →
	Indirect evidence “Ark Workplace Risk is the trusted partner for organisations seeking to take control of their risk, compliance, and safety.” Source: RevenueBase Database · checked Sep 14, 2026
9	Principle ONE	Strong evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	78 contacts →
	Strong evidence “Principle One provides Systems Engineering, Architecture and Business Consulting services within the Law Enforcement, National Security, Health and wider public sector.” Source: RevenueBase Database · checked Sep 14, 2026
10	Daintta	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	60 contacts →
	Indirect evidence “We provide deep expertise with technical and business specialists to help clients secure and protect the UK.” Source: RevenueBase Database · checked Sep 14, 2026
11	Assist Security Group	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	11-50	58 contacts →
	Partial evidence “Assist Security Group (ASG) helps clients build resilient, comprehensive security strategies that protect their people and assets, business continuity and reputation.” Source: RevenueBase Database · checked Sep 14, 2026
12	Black Diamond Security	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	201-500	58 contacts →
	Partial evidence “Black Diamond Security - Safeguarding Your World.” Source: RevenueBase Database · checked Sep 14, 2026
13	Hexegic	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	52 contacts →
	Indirect evidence “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: RevenueBase Database · checked Sep 14, 2026
14	Custom Intelligent Security	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	51 contacts →
	Partial evidence “Established in Custom Intelligent Security is a technology driven ISO27001 & NSi Gold Accredited independent electronic security specialist with a proven track record of…” Source: RevenueBase Database · checked Sep 14, 2026
15	GSA Global	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	11-50	49 contacts →
	Partial evidence “GSA Global helps organisations, families and individuals respond to serious, complex and emerging security risks.” Source: RevenueBase Database · checked Sep 14, 2026
16	Frankton Group LTD	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	48 contacts →
	Indirect evidence “In today’s complex threat environment, businesses, individuals, and organisations require trusted partners to provide the ultimate assurance that their assets are well protected.” Source: RevenueBase Database · checked Sep 14, 2026
17	Cornerstone	Strong evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	44 contacts →
	Strong evidence “CornerStone is an award winning, independent, security and digital building consulting firm with headquarters in the UK.” Source: RevenueBase Database · checked Sep 14, 2026
18	Ak9 Security And FM Solutions LTD	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	501-1,000	43 contacts →
	Partial evidence “AK9 Security and FM Solutions offers comprehensive security solutions for businesses, governmental organizations, and residential areas.” Source: RevenueBase Database · checked Sep 14, 2026
19	Gratte Brothers Security Systems & Software	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	39 contacts →
	Partial evidence “Gratte Brothers is an experienced provider of integrated security solutions, which are Built on Strong Values and ultimately deliver a measurable return on investment.” Source: RevenueBase Database · checked Sep 14, 2026
20	Secforce LTD	Strong evidence	London, United KingdomHQ checked Sep 14, 2026	11-50	39 contacts →
	Strong evidence “SECFORCE are vendor independent offensive security specialists providing effective business risk intelligence and strategic security consulting.” Source: RevenueBase Database · checked Sep 14, 2026
21	Audere Group	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	37 contacts →
	Indirect evidence “Audere Group is a London-headquartered holistic risk advisory company founded in 2014.” Source: RevenueBase Database · checked Sep 14, 2026
22	HAROD	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	11-50	36 contacts →
	Partial evidence “Harod Associates delivers global investigation and security solutions to complex crime and risk issues.” Source: RevenueBase Database · checked Sep 14, 2026
23	Venovox	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	35 contacts →
	Partial evidence “At VENOVOX, we are a premier consultancy in risk management and background screening, delivering specialised services in due diligence, security advisory, background checks, and…” Source: RevenueBase Database · checked Sep 14, 2026
24	Team Fusion LTD	Partial evidence	London, United KingdomHQ checked Sep 14, 2026	11-50	34 contacts →
	Partial evidence “Our elite teams offer bespoke, integrated security solutions that adapt and react to the evolving threat landscape.” Source: RevenueBase Database · checked Sep 14, 2026
25	Othrys	Indirect evidence	London, United KingdomHQ checked Sep 14, 2026	51-200	33 contacts →
	Indirect evidence “Othrys is a global strategic and risk advisory firm founded in 2016.” Source: RevenueBase Database · checked Sep 14, 2026

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: security consulting firms. 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 security consulting firms.
Partial evidence: Its own public description names part of security consulting firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name security consulting firms. 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 559 security consulting firms based in London, United Kingdom

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Security consulting firms based in London, United Kingdom at a glance

As of Sep 14, 2026

26.2%Verified-email coverage

9.8Average contacts per company

1-10Median size (employees)

100.0%Largest-city concentration · London

Sep 14, 2026Page data refreshed

Companies by employee count

1-10

325

11-50

160

51-200

201-500

501-1,000

1,001-5,000

5,001-10,000

10001+

Email recency for this list is measured across the whole United Kingdom list rather than for London, so it is reported there. Company counts and contact totals on this page are exact for London, over 559 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 security consulting firms, 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 London, United Kingdom whose own description of what they do matches “security consulting firms”. 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 security consulting firms), 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 security consulting firms, and records with no verified work email. Companies headquartered outside London 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, 1,441 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 14, 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 consulting firms by metro in the United Kingdom

Security consulting firms in London559
Security consulting firms in Manchester38
Security consulting firms in Birmingham30

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 security consulting firms, 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 security consulting firms are there based in London, United Kingdom?

RevenueBase identified 559 security consulting firms headquartered in London, 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?

Argenbright Security Europe Limited - Asel, headquartered in London, tops this list with the largest team on record.

Which city has the most security consulting firms?

London leads with 559 headquartered companies, followed by Manchester (38) and Birmingham (30).

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 1,441 verified decision-maker contacts tracked across these 559 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 14, 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 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.