Company lists · Data refreshed September 2026

Top 25 Mission critical systems security companies based in the United Kingdom

RevenueBase identified 1,133 company matches for mission critical systems security companies associated with the United Kingdom as of September 2026 and tracks 20,908 professional contacts across them, including 7,638 with verified work emails. London is the largest hub.

This list covers company matches for mission critical systems security companies associated with the United Kingdom, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed September 28, 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 RevenueBase SmartSearch · Exact Recorded Sep 28, 2026 How this list was built
1,133Companies
20,908Contacts tracked
7,638Verified emails
Explore this list → Free signup · no credit card · 500 free credits

The 25 largest mission critical systems security companies based in the United Kingdom

Ranked by team size
Top 25 of 1,133 company matches for mission critical systems security companies based in the United Kingdom, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Sep 28, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#CompanyRevenueBase SmartSearchHeadquartersEmployeesContacts
1Exact matchAbingdon, United KingdomHQ recorded Sep 28, 20265,001-10,0004,925 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
2Exact matchStaines-upon-thames, United KingdomHQ recorded Sep 28, 2026201-500764 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
3Exact matchSt Neots, United KingdomHQ recorded Sep 28, 2026201-500640 contacts →

Exact match

“MASS, part of the Cohort plc group, helps you realise the value of your data.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
4Exact matchLondon, United KingdomHQ recorded Sep 28, 2026501-1,000502 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
5Exact matchReading, United KingdomHQ recorded Sep 28, 2026201-500303 contacts →

Exact match

“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…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
6Exact matchEdinburgh, United KingdomHQ recorded Sep 28, 2026201-500297 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
7Exact matchLondon, United KingdomHQ recorded Sep 28, 2026201-500242 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
8Exact matchLondon, United KingdomHQ recorded Sep 28, 2026201-500190 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
9Exact matchNewcastle Upon Tyne, United KingdomHQ recorded Sep 28, 202651-200168 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
10Exact matchAlton, United KingdomHQ recorded Sep 28, 2026201-500165 contacts →

Exact match

“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…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
11Exact matchThatcham, United KingdomHQ recorded Sep 28, 202651-200159 contacts →

Exact match

“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…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
12Exact matchMaidenhead, United KingdomHQ recorded Sep 28, 202651-200156 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
13Exact matchBradley Stoke, United KingdomHQ recorded Sep 28, 2026201-500143 contacts →

Exact match

“Logiq is a UK-based cyber security consultancy and secure managed services provider supporting defence, government, and critical national infrastructure (CNI) organisations where…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
14Exact matchFleet, United KingdomHQ recorded Sep 28, 202651-200125 contacts →

Exact match

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

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
15Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-200123 contacts →

Exact match

“Bulletproof is now part of WorkNest Secure.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
16Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-200105 contacts →

Exact match

“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.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
17Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-20087 contacts →

Exact match

“ITC Secure is an advisory-led cyber security services company.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
18Exact matchStourport-on-severn, United KingdomHQ recorded Sep 28, 2026201-50086 contacts →

Exact match

“CyberGuard Technologies is the security division of Wavenet.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
19Exact matchBasingstoke, United KingdomHQ recorded Sep 28, 202611-5085 contacts →

Exact match

“Amethyst Risk Management is a leading cybersecurity consultancy supplying expert services and support to the UK Government, Defence, Operators of Essential Services, and the…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
20Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-20084 contacts →

Exact match

“Cybersecurity should be simple.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
21Exact matchSwindon, United KingdomHQ recorded Sep 28, 202651-20080 contacts →

Exact match

“When your business relies on security, compliance and a strong reputation for taking care of your customers, you need a partner that understands your ethos, your challenges and…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
22Exact matchWaterloo, United KingdomHQ recorded Sep 28, 202651-20080 contacts →

Exact match

“At Reliance Cyber, we believe in truly partnering with our customers.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
23Exact matchSouth & West Hampstead, United KingdomHQ recorded Sep 28, 202651-20079 contacts →

Exact match

“Virtual IT are a leading provider of cyber-secure cloud and managed IT services in the UK, entrusted by over 700 businesses and schools as their end-to-end technology partner.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
24Exact matchLondon, United KingdomHQ recorded Sep 28, 202651-20077 contacts →

Exact match

“White Hat, part of the EPAM group, is an award-winning cyber intelligence and offensive security company that leverages an attacker’s perspective to shape innovative, proactive…”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
25Exact matchOxford, United KingdomHQ recorded Sep 28, 202651-20073 contacts →

Exact match

“Dionach by Nomios has over 25 years of expertise in information security, supporting organisations in building resilience against ever‑evolving cyber threats.”

Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase

Showing 25 of 1,133 mission critical systems security companies based in the United Kingdom

See the full list, filter by size, metro and specialty, and access 7,638 tracked professional contacts with verified work emails. Direct dials are available where recorded.

Free signup · no credit card

View the full list →

Mission critical systems security companies based in the United Kingdom at a glance

As of Sep 28, 2026
36.5%Verified-email coverage
18.5Average contacts per company
1-10Median size (employees)
37.5%Largest-city concentration · London
Sep 28, 2026Page data refreshed

Companies by employee count

1-10
678
11-50
323
51-200
91
201-500
24
501-1,000
7
1,001-5,000
6
5,001-10,000
2
10001+
2

Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 1,133 companies.

How this list was built

The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.

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
Company records associated with the United Kingdom whose business descriptions match “mission critical systems security companies” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
RevenueBase SmartSearch
Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
Public preview
The public preview omits records without a verified work email. Where headquarters information is recorded, preview rows are also filtered to this page’s location. Dataset totals and geographic summaries describe the full matched records before these preview filters.
Match quality
RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
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 displayed company carries at least one verified work email. RevenueBase tracks 7,638 professional contacts with verified work emails across the full matched dataset. 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 28, 2026. Lists refresh periodically as the graph is re-checked.
Record context
Company records and descriptions can change. Check the company's website for its current services and locations.

Frequently asked

What is RevenueBase SmartSearch?

RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “mission critical systems security companies”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many mission critical systems security companies are there based in the United Kingdom?

RevenueBase identified 1,133 company matches for mission critical systems security companies associated with the United Kingdom as of September 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.

What is the largest company on this list?

Sophos tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which city has the most mission critical systems security companies?

London leads with 425 company records, followed by Manchester (46) and Birmingham (27).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 7,638 professional contacts with verified work emails tracked across these 1,133 companies; direct dials are available where recorded.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 28, 2026.

Ready to reach these companies? Verified emails and direct dials for all 1,133 mission critical systems security companies based in the United Kingdom. Start with a free account, no credit card.

Download this list →

Related lists

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.