Penetration Testing Companies in the UK: How to Choose (2026 Shortlist)

To shortlist penetration testing companies, UK buyers should check five things about each one before comparing prices: that every accreditation it claims appears on the scheme’s own register, who will actually do the testing, how much of the work is manual, what its reports look like, and whether a retest is included. Then compare quotes on tester-days, not the headline figure.

Who publishes this guide: Sovereign Secure Ltd publishes this page, and we sell penetration testing, so we are one of the companies you may be comparing. We do not rank providers, ourselves included, and we do not name competitors. Every criterion below comes from a published source you can read yourself. We review this guide every quarter; it was last reviewed in October 2026.

Key takeaways

• Verify accreditations on the awarding body’s register, not the provider’s website.
• You need CREST or CHECK only when a contract, tender, sponsor or scheme asks for it.
• The tester matters more than the brand. Ask who will do the work.
• Compare quotes by the number of manual testing days, not by the total.
• Ask for a sample report before you sign, and make sure a retest is part of the price.

What types of penetration testing firms are there in the UK?

UK pen testing companies fall into five broad types. None is better by default, so judge each against the scorecard below.

• Specialist testing firms: hands-on testing by small teams. Check capacity for your dates.
• Large consultancies: testing alongside audit and advisory work. Ask who actually tests.
• Managed service providers: testing bundled with IT support. Check independence if they run the systems tested.
• PTaaS platforms: tests booked and reported online. Ask how much is manual.
• Compliance-led firms: testing scoped around a standard such as PCI DSS. Check independence from any assessment they also do.

What should you look for in a penetration testing company?

Look for evidence you can check, not adjectives, and ask every provider to quote against the same written scope. Score each provider 0, 1 or 2 against each row of this scorecard; anything under 10 out of 16 deserves a hard second look. The last column gives the published source for each criterion.

Both main sources are free to read: the NCSC’s penetration testing guidance and the PCI SSC’s Penetration Testing Guidance in its document library.

Which accreditations matter, and how do you verify them?

The accreditation that matters is the one your contract, regulator or assessor asks for. Check it on the scheme’s register, because logos are easy to copy.

Also confirm the basics: the legal entity on Companies House, its registration with the ICO, and professional indemnity insurance at a level your contract needs.

CREST penetration testing and CHECK: do you need them?

Only when a contract, tender, sponsor or regulator-led scheme asks for one. CREST accredits companies and certifies testers; CHECK is the NCSC’s scheme for testing public sector and critical national infrastructure systems.

What is CREST?

CREST is an international not-for-profit membership body for the technical security industry. It accredits member companies against its own standards and certifies individual testers through exams. Commercial contracts and tenders often ask for it, and CREST is the accreditation and certification body for the Bank of England’s CBEST scheme. Check the company, and the services its accreditation covers, in CREST’s online directory.

What is CHECK?

CHECK is the scheme under which NCSC-assured companies carry out authorised penetration tests of public sector and critical national infrastructure (CNI) systems. The NCSC recommends that HMG organisations use CHECK testers and companies; other organisations are pointed to its general penetration testing guidance.

When do you need CREST or CHECK?

Sovereign Secure does not claim CREST or CHECK status. If your contract, tender or sponsor requires either, choose a provider that holds it and verify it on the register.

How much do UK penetration testing companies charge?

Most UK penetration tests cost between about £550 and £25,000, depending on scope. The figures below come from published prices from UK providers we reviewed in September 2026. They are market ranges, not Sovereign Secure prices.

Almost every quote is a day rate multiplied by an estimate of days, so a price far below the others usually means fewer days, or an automated scan with a report template. Our guide to penetration testing cost explains what drives the number of days.

How do you judge the scoping conversation?

A good provider asks detailed questions before quoting. Expect questions about:

• What you want tested: external infrastructure, internal network, web applications, APIs, mobile apps, cloud, wireless or people.
• How big each target is: live IP addresses, applications, user roles and API endpoints.
• What the systems hold and why you are testing: compliance, a customer contract, a launch or insurance.
• Black-box, grey-box or white-box testing.
• Constraints: fragile legacy kit, change freezes, third-party hosting.

Be cautious of a fixed price given without these questions. Give every shortlisted provider the same written answers, so the quotes you compare cover the same scope.

How much of the test should be manual?

Most of it. Every tester uses scanners, but a scan alone is not a penetration test. The value comes from a person who removes false positives, tests business logic and access control, and chains minor weaknesses into an attack path.

Ask how the tester’s days will be spent. If you only need routine automated coverage, vulnerability scanning services are cheaper and run more often. Our comparison of penetration testing vs vulnerability scanning sets out when you need each.

What should a sample report show?

Ask for a redacted sample report and judge it on clarity and specificity. A good one has a plain-English executive summary, evidenced findings with reproduction steps, risk ratings adjusted for your context rather than raw CVSS scores, and specific fixes rather than “follow best practice”. Our guide on how to read a penetration test report explains what each section should tell you.

Does the provider understand your compliance requirement?

• PCI DSS: Requirement 11.4 sets the scope, methodology, frequency, tester independence and retest rules. PCI DSS penetration testing should be scoped with segmentation testing in mind.
• ISO 27001: results should feed your risk treatment plan and support Annex A controls 8.8 and 8.29. See our page on ISO 27001 penetration testing.
• Cyber Essentials Plus: the audit is not a penetration test, and a pen test does not replace it.

What are the red flags?

• A quote with no scoping questions.
• No named testers, or reluctance to discuss experience.
• A sample report that reads like raw scanner output.
• Accreditation logos you cannot find on the scheme’s register.
• No written rules of engagement or authorisation.
• Pressure to sign a long-term contract before you have seen their work.

Questions to ask every shortlisted provider

1. Who will carry out the testing, and what is their experience with systems like ours?
2. How many days of manual testing are included, and what is automated?
3. Can we see a sample report?
4. Which methodology do you follow?
5. Is a retest included, and within what period?
6. How do you handle a critical finding during the test?
7. How is our data stored, and when is it deleted?
8. How will the report meet the compliance requirement behind this test?

Our checklist on how to prepare for a penetration test covers what you need ready once you have chosen.

Why doesn’t this guide rank providers?

Because a fair ranking is hard to produce when the publisher is one of the companies being ranked. UK advertising rules set a high bar for comparisons with competitors: the CAP Code’s rules on comparisons with identifiable competitors (section 3) and the Business Protection from Misleading Marketing Regulations 2008 require a comparison to cover products that meet the same need, to compare material, relevant, verifiable and representative features objectively, and not to mislead or denigrate. Where marketing reaches consumers, the unfair commercial practices rules in the Digital Markets, Competition and Consumers Act 2024 also apply.

So this guide gives you the criteria, sources and registers, and leaves the scoring to you. Apply the same test to any “best penetration testing companies” list: who published it, where did the publisher rank itself, and can every claim be checked?

Why Sovereign Secure

Sovereign Secure Ltd (company no. 08334453, established 2012) is headquartered in Accrington, Lancashire, close to clients who need penetration testing in Manchester and the North West. We are a PCI SSC Qualified Security Assessor (QSA) company, an IASME-licensed Cyber Essentials certification body and ISO 27001 certified, so our testing is scoped with the assessor’s evidence in mind.

Next step

Put the eight questions above to us as well as to anyone else on your list. Our penetration testing services UK page lists every test we run, and our pen test quote form gets you a fixed price.