Company lists · Data verified August 2026

Top 25 Cybersecurity defense contractors based in the United Kingdom

Name: Cybersecurity defense contractors based in the United Kingdom
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Verified Aug 28, 2026 1,081 companies tracked

There are 1,081 cybersecurity defense contractors headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 20,593 professional contacts across them, including 8,383 with verified work emails and 2,419 with mobile numbers. London is the largest hub.

This list covers cybersecurity defense contractors headquartered in the United Kingdom, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Data current as of August 28, 2026.

1,081Companies

20,593Contacts tracked

8,383Verified emails

2,419Mobile numbers

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The 25 largest cybersecurity defense contractors based in the United Kingdom

Ranked by team size

Top 25 of 1,081 cybersecurity defense contractors based in the United Kingdom, ranked by team size, largest first. Data verified Aug 28, 2026. Click a count to unlock that company's people.
#	Company	HQ	Employees	Contacts	Verified emails
1	Sophos	Abingdon	5,001-10,000	4,963	2,711
2	Zerofox	n/a	501-1,000	894	382
3	SISA	Leicester	201-500	739	253
4	ROKE	Manchester	1,001-5,000	684	410
5	Everfox	London	1,001-5,000	635	13
6	MASS	Lincoln	201-500	633	203
7	Withsecure	London	501-1,000	614	329
8	Bridewell	Edinburgh	201-500	304	189
9	Quorum Cyber	Edinburgh	201-500	292	177
10	The Redesign Group	London	201-500	201	140
11	Risk Associates - Emea & Asia	London	51-200	169	62
12	Exclusive Networks UK	Mansfield	201-500	168	118
13	Cyberfort	Thatcham	51-200	160	88
14	LOGIQ	Bristol	201-500	142	81
15	Cybersec Consulting	London	201-500	141	76
16	CCL Solutions Group	Stratford Upon Avon	51-200	136	68
17	Cipher سايڤر	London	201-500	135	50
18	Bulletproof Cyber Security	London	51-200	118	75
19	Cyberone	London	51-200	96	39
20	Softwerx	Cambridge	51-200	95	44
21	Wavenet Cyberguard	London	201-500	86	58
22	Cybersmart	London	51-200	83	55
23	Reliance Cyber	Waterloo	51-200	80	47
24	Saepio Information Security	High Wycombe	51-200	73	57
25	TDI Tetrad Digital Integrity	Windsor	51-200	71	39

Showing 25 of 1,081 cybersecurity defense contractors based in the United Kingdom

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Cybersecurity defense contractors based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 443 HQs

2,419Contacts with mobile numbers

14Emails re-verified in last 30 days

Companies by employee count

1-10

621

11-50

321

51-200

201-500

501-1,000

1,001-5,000

5,001-10,000

Cybersecurity defense contractors by metro

Metro	Companies
Cybersecurity defense contractors in London	443
Cybersecurity defense contractors in Manchester	42
Cybersecurity defense contractors in Cheltenham	22
Cybersecurity defense contractors in Birmingham	21
Cybersecurity defense contractors in Bristol	15
Cybersecurity defense contractors in Cambridge	13
Cybersecurity defense contractors in Edinburgh	12

How this list was built

Source: The RevenueBase company graph: 21.3 million companies and 398.9 million professional contacts resolved from primary sources.
Inclusion: Companies whose own business descriptions match “cybersecurity defense contractors”, with match quality audited by blind human judging, and headquartered in the United Kingdom.
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: Contact records re-verify on a rolling cadence; 14 contacts on this list were re-verified in the last 30 days.
Refresh: Lists are refreshed periodically as the underlying company graph is re-verified. Last verified Aug 28, 2026.

Frequently asked

How many cybersecurity defense contractors are there based in the United Kingdom?

There are 1,081 cybersecurity defense contractors headquartered in the United Kingdom as of August 2026 (RevenueBase).

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 cybersecurity defense contractors?

London leads with 443 headquartered companies, followed by Manchester (42) and Cheltenham (22).

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 8,383 verified decision-maker contacts tracked across these 1,081 companies.

How current is this list?

The list is refreshed periodically as the underlying company graph is re-verified. It was last verified on August 28, 2026.

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Related lists

Cybersecurity defense contractors by geography

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About this data

RevenueBase is a B2B contact data platform. Its company graph covers 21.3 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, the same data that powers RevenueBase's B2B data products and the free research portal.