Company lists · Data refreshed September 2026

Top 25 Critical infrastructure security firms based in London, United Kingdom

Name: Critical infrastructure 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 27, 2026 186 companies tracked

RevenueBase identified 186 critical infrastructure security firms headquartered in London, United Kingdom as of September 2026 and tracks 1,601 professional contacts across them, including 361 with verified work emails. Across the United Kingdom, London is the largest hub for this category.

This list covers critical infrastructure 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 27, 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 27, 2026 86% judged on-target in blind review

186Companies

1,601Contacts tracked

361Verified emails

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The 25 largest critical infrastructure security firms based in London, United Kingdom

Ranked by team size

Top 25 of 186 critical infrastructure security firms based in London, United Kingdom, ranked by team size, largest first. Data refreshed Sep 27, 2026. RevenueBase Smart Search rates how each company's information relates to critical infrastructure 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	Trpglobal	Indirect evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
2	AKE International	Indirect evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	89 contacts →
	Indirect evidence “We are proud of our unique track record.” Source: RevenueBase Database · checked Sep 27, 2026
3	Black Diamond Security	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	201-500	58 contacts →
	Partial evidence “Black Diamond Security - Safeguarding Your World.” Source: RevenueBase Database · checked Sep 27, 2026
4	Cyberowl	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	52 contacts →
	Strong evidence “CyberOwl helps asset operators in the maritime and critical national infrastructure sectors gain visibility, cyber security and cyber compliance of systems on their distributed…” Source: RevenueBase Database · checked Sep 27, 2026
5	Frankton Group LTD	Indirect evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
6	Cornerstone	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
7	Ak9 Security And FM Solutions LTD	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
8	Gratte Brothers Security Systems & Software	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
9	Audere Group	Indirect evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
10	Othrys	Indirect evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	33 contacts →
	Indirect evidence “Othrys is a global strategic and risk advisory firm founded in 2016.” Source: RevenueBase Database · checked Sep 27, 2026
11	Priavo Security	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
12	Se24	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	24 contacts →
	Partial evidence “A core member of the Chelsea Group Security & Crisis Management Division, Security Exchange is dedicated to the provision of specialist consultancy on a worldwide basis…” Source: RevenueBase Database · checked Sep 27, 2026
13	Anotherday	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	21 contacts →
	Partial evidence “AnotherDay is a new kind of defence & security consulting firm established to bring the power of effective intelligence and strategy to the challenge of safeguarding individuals…” Source: RevenueBase Database · checked Sep 27, 2026
14	LMS Security	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	20 contacts →
	Partial evidence “LMS Security are a fully Independent, privately owned, Internationally recognised and accredited Security Consultancy; owned and built by Electronic and Physical Security…” Source: RevenueBase Database · checked Sep 27, 2026
15	Cyber Energia	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	20 contacts →
	Partial evidence “Cyber Energia – Your Comprehensive Cyber Security Solution for a smart & sustainable energy market Cyber Energia is a dynamic managed security service provider offering OT / SCADA…” Source: RevenueBase Database · checked Sep 27, 2026
16	NGS Next Generation Security	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	20 contacts →
	Partial evidence “Formed in 2018, NGS (UK) Ltd are independent, Next Generation Security trusted advisors, providing all-encompassing solutions from the perimeter to the endpoint.” Source: RevenueBase Database · checked Sep 27, 2026
17	Optimal Risk Group LTD	Indirect evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	20 contacts →
	Indirect evidence “We optimise opportunities for our clients by managing their Risk & Resilience.” Source: RevenueBase Database · checked Sep 27, 2026
18	ALMA	Indirect evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	18 contacts →
	Indirect evidence “Your Partner Delivering Risk-Proof Success: UK-Based Expertise, Delivering Global Risk Management.” Source: RevenueBase Database · checked Sep 27, 2026
19	Excellentia Global	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	15 contacts →
	Partial evidence “Excellentia was established in 2006 to deliver specialist security and risk management solutions to clients in the United Kingdom.” Source: RevenueBase Database · checked Sep 27, 2026
20	Deltaflare	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	12 contacts →
	Strong evidence “deltaflare helps critical infrastructure operators modernise securely.” Source: RevenueBase Database · checked Sep 27, 2026
21	Veritas International	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	12 contacts →
	Partial evidence “We are a dedicated risk management consultancy, committed to delivering bespoke security solutions that align perfectly with your unique needs.” Source: RevenueBase Database · checked Sep 27, 2026
22	The Security Group	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	11 contacts →
	Partial evidence “The Security Group delivers state-of-the-art security solutions to protect businesses, assets, and people.” Source: RevenueBase Database · checked Sep 27, 2026
23	Icyberdefence	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	8 contacts →
	Partial evidence “iCyberDefence is a boutique cybersecurity services firm that offers a wide range of security consulting and security engineering services with the necessary products and tools.” Source: RevenueBase Database · checked Sep 27, 2026
24	Alliance Risk Management Solutions LTD	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	7 contacts →
	Partial evidence “ALLIANCE RISK MANAGEMENT SOLUTIONS LTD is a Security and Investigations company located in 2 Eaton Gate, London, LONDON, United Kingdom.” Source: RevenueBase Database · checked Sep 27, 2026
25	Valkyrie GB Limited	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	6 contacts →
	Partial evidence “At Valkyrie, our mission is rooted in a commitment to safeguarding our clients with the highest standards of security and discretion.” Source: RevenueBase Database · checked Sep 27, 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: critical infrastructure 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 critical infrastructure security firms.
Partial evidence: Its own public description names part of critical infrastructure security firms, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name critical infrastructure 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 186 critical infrastructure security firms based in London, United Kingdom

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Critical infrastructure security firms based in London, United Kingdom at a glance

As of Sep 27, 2026

22.5%Verified-email coverage

8.6Average contacts per company

11-50Median size (employees)

Sep 27, 2026Page data refreshed

Companies by employee count

1-10

11-50

51-200

201-500

501-1,000

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 186 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 critical infrastructure 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 “critical infrastructure 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 critical infrastructure 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 critical infrastructure 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, 361 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 27, 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.

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 critical infrastructure 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 critical infrastructure security firms are there based in London, United Kingdom?

RevenueBase identified 186 critical infrastructure 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?

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

Which city in the United Kingdom has the most critical infrastructure security firms?

London leads the United Kingdom with 186 headquartered companies, followed by Manchester (9) and Bristol (8).

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 361 verified decision-maker contacts tracked across these 186 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 27, 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.