Company lists · Data verified August 2026

Top 25 Cybersecurity incident response firms based in the United Kingdom

Name: Cybersecurity incident response firms 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 706 companies tracked

There are 706 cybersecurity incident response firms headquartered in the United Kingdom (RevenueBase, August 2026). RevenueBase tracks 14,396 professional contacts across them, including 5,824 with verified work emails and 1,737 with mobile numbers. London is the largest hub.

This list covers cybersecurity incident response firms 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.

706Companies

14,396Contacts tracked

5,824Verified emails

1,737Mobile numbers

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The 25 largest cybersecurity incident response firms based in the United Kingdom

Ranked by team size

Top 25 of 706 cybersecurity incident response firms 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	SISA	Leicester	201-500	739	253
2	Everfox	London	1,001-5,000	635	13
3	Withsecure	London	501-1,000	614	329
4	Bridewell	Edinburgh	201-500	304	189
5	Cyberfort	Thatcham	51-200	160	88
6	Cybersec Consulting	London	201-500	141	76
7	CCL Solutions Group	Stratford Upon Avon	51-200	136	68
8	Khipu Networks	Fleet	51-200	129	94
9	Bulletproof Cyber Security	London	51-200	118	75
10	Sep2	London	51-200	99	20
11	Cyberone	London	51-200	96	39
12	Softwerx	Cambridge	51-200	95	44
13	ITC Secure	London	51-200	87	39
14	Wavenet Cyberguard	London	201-500	86	58
15	Cybersmart	London	51-200	83	55
16	Reliance Cyber	Waterloo	51-200	80	47
17	Saepio Information Security	High Wycombe	51-200	73	57
18	Izoologic	City Of London	201-500	67	48
19	Cyro Cyber	London	51-200	63	10
20	Daintta	London	51-200	61	18
21	Digitalxraid	Doncaster	51-200	59	39
22	Cyberlab	Lincoln	51-200	56	41
23	Istari	London	51-200	53	29
24	Hexegic	London	51-200	52	30
25	Redscan, A Kroll Business	London	51-200	52	29

Showing 25 of 706 cybersecurity incident response firms based in the United Kingdom

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Cybersecurity incident response firms based in the United Kingdom at a glance

As of Aug 28, 2026

1-10Median size (employees)

LondonLargest hub · 306 HQs

1,737Contacts with mobile numbers

12Emails re-verified in last 30 days

Companies by employee count

1-10

405

11-50

210

51-200

201-500

501-1,000

1,001-5,000

10001+

Cybersecurity incident response firms by metro

Metro	Companies
Cybersecurity incident response firms in London	306
Cybersecurity incident response firms in Manchester	29
Cybersecurity incident response firms in Cheltenham	17
Cybersecurity incident response firms in Birmingham	11
Cybersecurity incident response firms in Cambridge	10
Cybersecurity incident response firms in Bristol	8
Cybersecurity incident response firms in Milton Keynes	8

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 incident response firms”, 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; 12 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 incident response firms are there based in the United Kingdom?

There are 706 cybersecurity incident response firms headquartered in the United Kingdom as of August 2026 (RevenueBase).

What is the largest company on this list?

SISA, headquartered in Leicester, tops this list with the largest team on record.

Which city has the most cybersecurity incident response firms?

London leads with 306 headquartered companies, followed by Manchester (29) and Cheltenham (17).

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 5,824 verified decision-maker contacts tracked across these 706 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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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.