Company lists · Data refreshed September 2026

Top 25 Managed security service providers based in the United Kingdom

RevenueBase identified 1,497 managed security service providers headquartered in the United Kingdom as of September 2026 and tracks 28,419 professional contacts across them, including 11,493 with verified work emails and 2,980 with mobile numbers. London is the largest hub.

This list covers managed security service providers headquartered in the 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 5, 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 5, 2026 86% judged on-target in blind review
1,497Companies
28,419Contacts tracked
11,493Verified emails
2,980Mobile numbers
Unlock all 1,497 companies Free signup · no credit card · 500 free credits

The 25 largest managed security service providers based in the United Kingdom

Ranked by team size
Top 25 of 1,497 managed security service providers based in the United Kingdom, ranked by team size, largest first. Data refreshed Sep 5, 2026. Evidence rates how directly each company's own description names managed security service providers: 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.
#CompanyHeadquartersEmployeesContacts
1
SophosIndirect evidence
Abingdon, United KingdomHQ checked Sep 5, 20265,001-10,0004,925

“Sophos is a cybersecurity leader defending organizations globally with an AI-driven platform and expert-led services.”

Source: company website · checked Sep 5, 2026
2
DarktraceIndirect evidence
Cambridge, United KingdomHQ checked Sep 5, 20261,001-5,0002,355

“Darktrace is a global leader in AI cybersecurity, providing the essential cybersecurity platform to secure organizations today and for an ever-changing future.”

Source: company website · checked Sep 5, 2026
3
MTIPartial evidence
Staines-upon-thames, United KingdomHQ checked Sep 5, 2026201-500764

“MTI provides award-winning, end-to-end technology solutions and services in cyber security and data centre for over 35 years.”

Source: company website · checked Sep 5, 2026
4
SecurityhqPartial evidence
London, United KingdomHQ checked Sep 5, 2026501-1,000502

SecurityHQ, a global cybersecurity company pioneering Security Performance Engineering for stronger operational performance and resilience.”

Source: company website · checked Sep 5, 2026
5
S-RmPartial evidence
London, United KingdomHQ checked Sep 5, 2026201-500351

“S-RM is a global intelligence and cyber security consultancy.”

Source: company website · checked Sep 5, 2026
6
BridewellPartial evidence
Reading, United KingdomHQ checked Sep 5, 2026201-500303

“Bridewell is the trusted cyber security partner for organisations operating within Critical National Infrastructure (CNI), as well as companies who want the highest standard of…”

Source: company website · checked Sep 5, 2026
7
Quorum CyberIndirect evidence
Edinburgh, United KingdomHQ checked Sep 5, 2026201-500297

“At Quorum Cyber, we're on a mission to help good people win.”

Source: company website · checked Sep 5, 2026
8
XalientPartial evidence
Leeds, United KingdomHQ checked Sep 5, 2026201-500260

“We are a global boutique, specializing exclusively in the convergence of identity-driven security and networking.”

Source: company website · checked Sep 5, 2026
9
ObrelaPartial evidence
London, United KingdomHQ checked Sep 5, 2026201-500242

“Obrela Security Industries is a global provider of cyber security services.”

Source: company website · checked Sep 5, 2026
10
IntragenStrong evidence
London, United KingdomHQ checked Sep 5, 2026201-500190

“Intragen is a cyber security business focused on managed Identity solutions and services.”

Source: company website · checked Sep 5, 2026
11
Atech CloudStrong evidence
Marlow, United KingdomHQ checked Sep 5, 202651-200178

“24 x 7 Cloud Service Provider & Managed Security Service Provider delivering technology transformation.”

Source: company website · checked Sep 5, 2026
12
Deepcytes Cyber Labs UKIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-200177

“Whether you’re a business or an individual, digital threats to your precious data and assets can come in any form - external or internal.”

Source: company website · checked Sep 5, 2026
13
SapphirePartial evidence
Newcastle Upon Tyne, United KingdomHQ checked Sep 5, 202651-200168

“Sapphire delivers comprehensive cyber solutions tailored to your needs, spanning across consultancy, managed services, IT/OT and beyond.”

Source: company website · checked Sep 5, 2026
14
Exclusive Networks UKIndirect evidence
Alton, United KingdomHQ checked Sep 5, 2026201-500165

“Exclusive Networks is a global trusted cybersecurity specialist for digital infrastructure helping to drive the transition to a totally trusted digital future for all people and…”

Source: company website · checked Sep 5, 2026
15
FournetIndirect evidence
Manchester, United KingdomHQ checked Sep 5, 2026201-500165

“FourNet transforms the customer and citizen services people rely on every day.”

Source: company website · checked Sep 5, 2026
16
CyberfortPartial evidence
Thatcham, United KingdomHQ checked Sep 5, 202651-200159

“At Cyberfort we are passionate about the cyber security services we deliver for our customers which keeps their people, data, systems and technology infrastructure secure…”

Source: company website · checked Sep 5, 2026
17
PerformantaPartial evidence
Maidenhead, United KingdomHQ checked Sep 5, 202651-200156

“Performanta is a global cybersecurity and data risk management company dedicated to protecting people where data matters most.”

Source: company website · checked Sep 5, 2026
18
Khipu NetworksPartial evidence
Fleet, United KingdomHQ checked Sep 5, 202651-200125

“KHIPU Networks is an award winning international Cyber Security Company delivering a wide range of network, wireless and security solutions, technologies and services across…”

Source: company website · checked Sep 5, 2026
19
Bulletproof Cyber SecurityIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-200123

“Bulletproof is now part of WorkNest Secure.”

Source: company website · checked Sep 5, 2026
20
Doherty AssociatesStrong evidence
London, United KingdomHQ checked Sep 5, 202651-200113

“Doherty Associates is a Managed Service Provider delivering IT support, cyber security and AI enablement ‘beyond the call’.”

Source: company website · checked Sep 5, 2026
21
RED SiftIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-200109

“Red Sift enables organizations to anticipate, respond to, and recover from cyber attacks while continuing to operate effectively.”

Source: company website · checked Sep 5, 2026
22
ConoscoIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-200105

“Cybersecurity specialists providing technology and telecoms solutions that gives you the leadership, experience and resilience you need to build and secure the future of work.”

Source: company website · checked Sep 5, 2026
23
OryxalignIndirect evidence
London, United KingdomHQ checked Sep 5, 202651-20099

“OryxAlign creates true alignment that delivers the right outcomes for all.”

Source: company website · checked Sep 5, 2026
24London, United KingdomHQ checked Sep 5, 2026201-50097

“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 5, 2026
25
CyberoneStrong evidence
London, United KingdomHQ checked Sep 5, 202651-20096

“CyberOne is a Microsoft Security Elite Partner and one of only 100 global Microsoft partners recognised with Microsoft-Verified Managed XDR solution status.”

Source: company website · checked Sep 5, 2026

Showing 25 of 1,497 managed security service providers based in the United Kingdom

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Managed security service providers based in the United Kingdom at a glance

As of Sep 5, 2026
1-10Median size (employees)
LondonLargest hub · 564 HQs
2,980Contacts with mobile numbers
Sep 5, 2026Data refreshed

Companies by employee count

1-10
856
11-50
457
51-200
133
201-500
33
501-1,000
7
1,001-5,000
7
5,001-10,000
2
10001+
1

Verified emails by last verification

0–30
10,642
31–60
707
61–90
5
90–180
1
180+
138

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 managed security service providers, 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 the United Kingdom whose own description of what they do matches “managed security service providers”. 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 managed security service providers, and records with no verified work email. Companies headquartered outside United Kingdom 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, 11,493 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 5, 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

How many managed security service providers are there based in the United Kingdom?

RevenueBase identified 1,497 managed security service providers headquartered in the 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?

Sophos, headquartered in Abingdon, tops this list with the largest team on record.

Which city has the most managed security service providers?

London leads with 564 headquartered companies, followed by Manchester (59) and Birmingham (31).

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 11,493 verified decision-maker contacts tracked across these 1,497 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 5, 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.