Company lists · Data refreshed September 2026

Top 25 Financial services security firms based in London, United Kingdom

Name: Financial services security 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 28, 2026 390 companies tracked

RevenueBase identified 390 financial services security firms headquartered in London, United Kingdom as of September 2026 and tracks 85,498 professional contacts across them, including 1,153 with verified work emails. Across the United Kingdom, London is the largest hub for this category.

This list covers financial services security 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 28, 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 28, 2026 86% judged on-target in blind review

390Companies

85,498Contacts tracked

1,153Verified emails

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The 25 largest financial services security firms based in London, United Kingdom

Ranked by team size

Top 25 of 390 financial services security firms based in London, United Kingdom, ranked by team size, largest first. Data refreshed Sep 28, 2026. RevenueBase Smart Search rates how each company's information relates to financial services security 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	G4s	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	10001+	79,699 contacts →
	Partial evidence “G4S is a leading security and facility services company that provides proactive security services and cutting-edge smart technology to deliver tailored, integrated security…” Source: RevenueBase Database · checked Sep 28, 2026
2	CIS Security Limited	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	1,001-5,000	919 contacts →
	Partial evidence “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.” Source: RevenueBase Database · checked Sep 28, 2026
3	Obrela	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	201-500	242 contacts →
	Partial evidence “Obrela Security Industries is a global provider of cyber security services.” Source: RevenueBase Database · checked Sep 28, 2026
4	The Keyholding Company	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	51-200	137 contacts →
	Partial evidence “The Keyholding Company are a tech-enabled mobile security services company, specialising in alarm response, mobile patrols, locks and unlocks, emergency and temporary guarding…” Source: RevenueBase Database · checked Sep 28, 2026
5	Trpglobal	Indirect evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
6	Lead Element Security Group	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	51-200	75 contacts →
	Partial evidence “We are Veteran Owned, Veteran Operated Security company based in London (HQ), with operation nationwide.” Source: RevenueBase Database · checked Sep 28, 2026
7	City Security Services Part Of City Group Security	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	201-500	64 contacts →
	Partial evidence “City Security Services (CSS) have more than 25 years’ experience within the corporate security, public sector, education and social housing markets delivering manned guarding…” Source: RevenueBase Database · checked Sep 28, 2026
8	Assist Security Group	Partial evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
9	Black Diamond Security	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	201-500	58 contacts →
	Partial evidence “Black Diamond Security - Safeguarding Your World.” Source: RevenueBase Database · checked Sep 28, 2026
10	Hexegic	Indirect evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
11	Custom Intelligent Security	Partial evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
12	Frankton Group LTD	Indirect evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
13	UK Protection LTD	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	201-500	45 contacts →
	Partial evidence “UK Protection is widely recognised as the premier supplier of security solutions to the Corporate, Jewellery and Luxury Retail industries across the UK.” Source: RevenueBase Database · checked Sep 28, 2026
14	Cornerstone	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	51-200	44 contacts →
	Partial evidence “CornerStone is an award winning, independent, security and digital building consulting firm with headquarters in the UK.” Source: RevenueBase Database · checked Sep 28, 2026
15	Ak9 Security And FM Solutions LTD	Partial evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
16	Gratte Brothers Security Systems & Software	Partial evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
17	BML Group	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	37 contacts →
	Partial evidence “Founded in 2015, BML Group is one of the UK's leading Security & Facilities Management providers, delivering tailored solutions that enhance operational efficiency and safety.” Source: RevenueBase Database · checked Sep 28, 2026
18	HAROD	Partial evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
19	Team Fusion LTD	Partial evidence	London, United KingdomHQ checked Sep 28, 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 28, 2026
20	Cyb3r	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	51-200	32 contacts →
	Partial evidence “CYB3R Group, is a leading provider of comprehensive Cyber Security, IT and Communications Solutions.” Source: RevenueBase Database · checked Sep 28, 2026
21	Capstar	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	51-200	30 contacts →
	Partial evidence “Capstar provides technology-enabled threat, risk and security services to private and corporate clients.” Source: RevenueBase Database · checked Sep 28, 2026
22	J2 Mssp	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	29 contacts →
	Partial evidence “Cyber security is the modern business' greatest risk.” Source: RevenueBase Database · checked Sep 28, 2026
23	Priavo Security	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	28 contacts →
	Partial evidence “Priavo Security Group is an established provider of comprehensive security risk management, dedicated to safeguarding individuals, information, assets, and reputation through…” Source: RevenueBase Database · checked Sep 28, 2026
24	Nanjgel Solutions	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	51-200	24 contacts →
	Partial evidence “Nanjgel Solutions is focused on delivering the best IT security for businesses.” Source: RevenueBase Database · checked Sep 28, 2026
25	Kiris Group	Partial evidence	London, United KingdomHQ checked Sep 28, 2026	11-50	22 contacts →
	Partial evidence “Our Chartered Security Professionals seamlessly integrate discreet and effective security into lifestyles and organisations.” Source: RevenueBase Database · checked Sep 28, 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: financial services security 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 financial services security firms.
Partial evidence: Its own public description names part of financial services security firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name financial services security 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 390 financial services security firms based in London, United Kingdom

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Financial services security firms based in London, United Kingdom at a glance

As of Sep 28, 2026

1.3%Verified-email coverage

219.2Average contacts per company

11-50Median size (employees)

Sep 28, 2026Page data refreshed

Companies by employee count

1-10

168

11-50

130

51-200

201-500

501-1,000

1,001-5,000

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 390 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 financial services security 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 “financial services security 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 financial services security 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 financial services security 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, 1,153 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 28, 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.

Financial services security firms by metro in the United Kingdom

Financial services security firms in Birmingham27

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 financial services security 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 financial services security firms are there based in London, United Kingdom?

RevenueBase identified 390 financial services security 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?

G4s, headquartered in London, tops this list with the largest team on record.

Which city in the United Kingdom has the most financial services security firms?

London leads the United Kingdom with 390 headquartered companies, followed by Manchester (28) and Birmingham (27).

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 1,153 verified decision-maker contacts tracked across these 390 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 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 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.