Company lists · Data refreshed September 2026

Top 24 Building management system security companies based in London, United Kingdom

Name: Building management system security companies 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 234 companies tracked

RevenueBase identified 234 building management system security companies headquartered in London, United Kingdom as of September 2026 and tracks 82,827 professional contacts across them, including 970 with verified work emails. Across the United Kingdom, London is the largest hub for this category.

This list covers building management system security companies 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

234Companies

82,827Contacts tracked

970Verified emails

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The 24 largest building management system security companies based in London, United Kingdom

Ranked by team size

Top 24 of 234 building management system security companies 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 building management system security companies: 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 27, 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 27, 2026
2	CIS Security Limited	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
3	QCIC	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	159 contacts →
	Strong evidence “QCIC is an award-winning global engineering firm specialising in designing, building and running security systems.” Source: RevenueBase Database · checked Sep 27, 2026
4	The Keyholding Company	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
5	3mse LTD	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	74 contacts →
	Strong evidence “3MSe Ltd are an experienced provider of turnkey Building Management Systems.” Source: RevenueBase Database · checked Sep 27, 2026
6	City Security Services Part Of City Group Security	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
7	WLS	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	61 contacts →
	Partial evidence “WLS (West London Security) has been providing security and solutions to London's homes and businesses for over 40 years.” Source: RevenueBase Database · checked Sep 27, 2026
8	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
9	Custom Intelligent Security	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
10	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
11	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
12	Universal Security Systems LTD	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	39 contacts →
	Strong evidence “Universal Security Systems Limited is a specialist provider of installation and maintenance services for all types of security systems including Access Control, Closed Circuit…” Source: RevenueBase Database · checked Sep 27, 2026
13	BML Group	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	37 contacts →
	Strong 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 27, 2026
14	Team Fusion LTD	Partial evidence	London, United KingdomHQ checked Sep 27, 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 27, 2026
15	Pafi LTD	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	32 contacts →
	Partial evidence “Pafi Ltd, Was formed in 1995 to design, install and maintain integrated security solutions for the commercial market.” Source: RevenueBase Database · checked Sep 27, 2026
16	Okto Technologies	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	32 contacts →
	Strong evidence “Master Systems Integrator OKTO Technologies is a leader in the design, development & installation of Smart Building Technology for- SuperPrime Residential - Luxury Hospitality -…” Source: RevenueBase Database · checked Sep 27, 2026
17	DS Security Group LTD	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	27 contacts →
	Partial evidence “CCTV and Access Control Service and installation specialists Established in 1993 DS Security prides itself on customer service.” Source: RevenueBase Database · checked Sep 27, 2026
18	ALL BMS Systems LTD	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	27 contacts →
	Strong evidence “All BMS Systems offer a comprehensive service covering consultancy, design, project management, engineering, installation and all essential support services.” Source: RevenueBase Database · checked Sep 27, 2026
19	Welcome Gate	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	23 contacts →
	Strong evidence “Who are you… Most likely you are a Workplace or IT Professional with a lot on your plate including physical electronic security systems, such as - Access control - CCTV - Intruder…” Source: RevenueBase Database · checked Sep 27, 2026
20	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
21	The Portmarnock Group	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	19 contacts →
	Partial evidence “The Portmarnock Group was built from years of experience, hard work and a genuine passion for doing security differently.” Source: RevenueBase Database · checked Sep 27, 2026
22	Cyberrey	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	11-50	18 contacts →
	Strong evidence “Your Trusted Distribution & Security Solutions in Building and Securing Your Digital Ecosystem Cyberrey is a leading distributor of comprehensive cybersecurity solutions…” Source: RevenueBase Database · checked Sep 27, 2026
23	Siemsatec LTD	Strong evidence	London, United KingdomHQ checked Sep 27, 2026	1-10	17 contacts →
	Strong evidence “Established in 2004, Siemsatec Ltd are an independent building management systems (BMS) and energy management specialists.” Source: RevenueBase Database · checked Sep 27, 2026
24	Line Security Services LTD	Partial evidence	London, United KingdomHQ checked Sep 27, 2026	51-200	17 contacts →
	Partial evidence “As a security services provider, protecting people and assets is our top priority.” 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: building management system security companies. 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 building management system security companies.
Partial evidence: Its own public description names part of building management system security companies, so it works in or next to the category without describing itself that way.
Indirect evidence: The description shown does not name building management system security companies. 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 24 of 234 building management system security companies based in London, United Kingdom

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Building management system security companies based in London, United Kingdom at a glance

As of Sep 27, 2026

1.2%Verified-email coverage

354.0Average contacts per company

11-50Median size (employees)

Sep 27, 2026Page data refreshed

Companies by employee count

1-10

107

11-50

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 234 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 building management system security companies, 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 “building management system security companies”. 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 building management system security companies), 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 building management system security companies, 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, 970 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.

Building management system security companies by metro in the United Kingdom

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 building management system security companies, 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 building management system security companies are there based in London, United Kingdom?

RevenueBase identified 234 building management system security companies 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 building management system security companies?

London leads the United Kingdom with 234 headquartered companies, followed by Manchester (33) 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 970 verified decision-maker contacts tracked across these 234 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.