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 6, 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, 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.

How to read this list HQ checked on every row Match evidence on every row Refreshed Sep 6, 2026 86% judged on-target in blind review

559Companies

5,491Contacts tracked

1,441Verified emails

Explore all 559 companies → Free signup · no credit card · 500 free credits

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 6, 2026. Evidence rates how directly each company's own description names security consulting firms: strong (names it), partial (names part of it), indirect (matched on its full profile rather than the summary shown). Click a count to unlock that company's people.
#	Company	Headquarters	Employees	Contacts
1	Argenbright Security Europe Limited - AselPartial evidence	London, United KingdomHQ checked Sep 6, 2026	5,001-10,000	358
	“ASEL design, develop and deliver fully bespoke and integrated security solutions, seamlessly bringing together people, technology and processes to achieve results-driven outcomes.” Source: company website · checked Sep 6, 2026
2	ObrelaPartial evidence	London, United KingdomHQ checked Sep 6, 2026	201-500	242
	“Obrela Security Industries is a global provider of cyber security services.” Source: company website · checked Sep 6, 2026
3	Turnkey ConsultingStrong evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	134
	“Turnkey Consulting brings together people, protection, and performance to help the world’s leading companies understand and optimize their risk and security landscape.” Source: company website · checked Sep 6, 2026
4	TrpglobalIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	126
	“We are TRPGLOBAL, your strategic partner in helping you with the complexities of risk management.” Source: company website · checked Sep 6, 2026
5	Bulletproof Cyber SecurityIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	123
	“Bulletproof is now part of WorkNest Secure.” Source: company website · checked Sep 6, 2026
6	Caretower An Integrity360 CompanyPartial evidence	London, United KingdomHQ checked Sep 6, 2026	201-500	97
	“As an independent IT security specialist, Caretower provide comprehensive solutions to individual problems, thus allowing our recommendations to be unbiased.” Source: company website · checked Sep 6, 2026
7	ITC SecurePartial evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	87
	“ITC Secure is an advisory-led cyber security services company.” Source: company website · checked Sep 6, 2026
8	ARK Workplace RiskIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	82
	“Ark Workplace Risk is the trusted partner for organisations seeking to take control of their risk, compliance, and safety.” Source: company website · checked Sep 6, 2026
9	Principle ONEStrong evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	78
	“Principle One provides Systems Engineering, Architecture and Business Consulting services within the Law Enforcement, National Security, Health and wider public sector.” Source: company website · checked Sep 6, 2026
10	DainttaIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	60
	“We provide deep expertise with technical and business specialists to help clients secure and protect the UK.” Source: company website · checked Sep 6, 2026
11	Assist Security GroupPartial evidence	London, United KingdomHQ checked Sep 6, 2026	11-50	58
	“Assist Security Group (ASG) helps clients build resilient, comprehensive security strategies that protect their people and assets, business continuity and reputation.” Source: company website · checked Sep 6, 2026
12	Black Diamond SecurityPartial evidence	London, United KingdomHQ checked Sep 6, 2026	201-500	58
	“Black Diamond Security - Safeguarding Your World.” Source: company website · checked Sep 6, 2026
13	HexegicIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	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, 2026
14	Custom Intelligent SecurityPartial evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	51
	“Established in Custom Intelligent Security is a technology driven ISO27001 & NSi Gold Accredited independent electronic security specialist with a proven track record of…” Source: company website · checked Sep 6, 2026
15	GSA GlobalPartial evidence	London, United KingdomHQ checked Sep 6, 2026	11-50	49
	“GSA Global helps organisations, families and individuals respond to serious, complex and emerging security risks.” Source: company website · checked Sep 6, 2026
16	Frankton Group LTDIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	48
	“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: company website · checked Sep 6, 2026
17	CornerstoneStrong evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	44
	“CornerStone is an award winning, independent, security and digital building consulting firm with headquarters in the UK.” Source: company website · checked Sep 6, 2026
18	Ak9 Security And FM Solutions LTDPartial evidence	London, United KingdomHQ checked Sep 6, 2026	501-1,000	43
	“AK9 Security and FM Solutions offers comprehensive security solutions for businesses, governmental organizations, and residential areas.” Source: company website · checked Sep 6, 2026
19	Gratte Brothers Security Systems & SoftwarePartial evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	39
	“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: company website · checked Sep 6, 2026
20	Secforce LTDStrong evidence	London, United KingdomHQ checked Sep 6, 2026	11-50	39
	“SECFORCE are vendor independent offensive security specialists providing effective business risk intelligence and strategic security consulting.” Source: company website · checked Sep 6, 2026
21	Audere GroupIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	37
	“Audere Group is a London-headquartered holistic risk advisory company founded in 2014.” Source: company website · checked Sep 6, 2026
22	HARODPartial evidence	London, United KingdomHQ checked Sep 6, 2026	11-50	36
	“Harod Associates delivers global investigation and security solutions to complex crime and risk issues.” Source: company website · checked Sep 6, 2026
23	VenovoxPartial evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	35
	“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: company website · checked Sep 6, 2026
24	Team Fusion LTDPartial evidence	London, United KingdomHQ checked Sep 6, 2026	11-50	34
	“Our elite teams offer bespoke, integrated security solutions that adapt and react to the evolving threat landscape.” Source: company website · checked Sep 6, 2026
25	OthrysIndirect evidence	London, United KingdomHQ checked Sep 6, 2026	51-200	33
	“Othrys is a global strategic and risk advisory firm founded in 2016.” Source: company website · checked Sep 6, 2026

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 6, 2026

1-10Median size (employees)

LondonLargest hub · 559 HQs

Contacts with mobile numbers

Sep 6, 2026Data 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 this city, 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 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 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.
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 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, 1,441 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 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 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

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 6, 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.