Top 10 security companies in the UK (2026)
These are the ten biggest security companies in the UK, ranked by UK security turnover in Infologue’s Top 100 UK Security Companies 2025. For each firm you will find its turnover, what it is known for and who it may suit, followed by how to choose between a national provider and a regional specialist, and the checks to make before you sign.
The 10 biggest security companies in the UK
| # | Company | UK security turnover (2025) |
|---|---|---|
| 1 | Mitie | £1,179m |
| 2 | Allied Universal / G4S | £710m (incl. TSS) |
| 3 | OCS Group UK | £395m |
| 4 | Securitas Security Services | £345m |
| 5 | Bidvest Noonan | £302m |
| 6 | CIS Security | £180m |
| 7 | Kingdom | £175m |
| 8 | ICTS (UK) | £166m |
| 9 | Wilson James | £142m |
| 10 | ASEL | £132m |
Source: Infologue Top 100 UK Security Companies 2025. Figures are as published by Infologue.
What each of the top security firms is known for
Short summaries of the leading security companies in the UK. Check each firm’s own website for current services and coverage.
1.Mitie
- UK security turnover
- £1,179m (Infologue 2025)
- Known for
- One of the UK’s largest facilities management groups, with security as one of its biggest divisions.
- May suit
- Large organisations that want security managed alongside cleaning and wider facilities services.
2.Allied Universal / G4S
- UK security turnover
- £710m (incl. TSS) (Infologue 2025)
- Known for
- Allied Universal completed its takeover of G4S in 2021, bringing together two of the world’s biggest security businesses.
- May suit
- Multi-site and public sector contracts that need national scale.
3.OCS Group UK
- UK security turnover
- £395m (Infologue 2025)
- Known for
- A facilities services group whose UK work includes security alongside cleaning and other support services.
- May suit
- Buyers bundling security into a wider facilities contract.
4.Securitas Security Services
- UK security turnover
- £345m (Infologue 2025)
- Known for
- The UK business of the Swedish Securitas group, offering manned guarding alongside mobile and remote security services.
- May suit
- Organisations that want guarding combined with mobile patrols and remote monitoring.
5.Bidvest Noonan
- UK security turnover
- £302m (Infologue 2025)
- Known for
- Part of the Bidvest Group, providing security and facility services across the UK and Ireland.
- May suit
- Corporate, retail and public sector sites in the UK and Ireland.
6.CIS Security
- UK security turnover
- £180m (Infologue 2025)
- Known for
- A UK company providing SIA-regulated security services.
- May suit
- Buyers comparing large providers for guarding contracts.
7.Kingdom
- UK security turnover
- £175m (Infologue 2025)
- Known for
- A UK group providing security alongside other services such as cleaning and environmental enforcement.
- May suit
- Councils and organisations that want several services from one supplier.
8.ICTS (UK)
- UK security turnover
- £166m (Infologue 2025)
- Known for
- Part of the international ICTS group, known for aviation and transport security.
- May suit
- Airports, transport hubs and other high-security environments.
9.Wilson James
- UK security turnover
- £142m (Infologue 2025)
- Known for
- A UK provider of security, aviation services and construction logistics.
- May suit
- Major construction projects and corporate estates.
10.ASEL
- UK security turnover
- £132m (Infologue 2025)
- Known for
- A UK company providing SIA-regulated security services.
- May suit
- Buyers comparing large providers for guarding contracts.
Biggest is not always best: national firm or regional specialist?
The major security companies offer national coverage, large workforces and the depth to run multi-site contracts. That suits organisations with sites across the country or complex public sector requirements.
A regional specialist can suit you better when you have one site or a handful in the same area. You are more likely to deal directly with the managers who run your contract, supervisors can visit in person, and local response can be quicker. Whichever route you take, judge the company on fit, checks and references rather than turnover alone.
A regional specialist to consider in the North West: USSG
We publish this guide, so we are telling you that up front. Universal Support Services Group (USSG) is an SIA Approved Contractor founded in 2016 and based in Stockport, Greater Manchester. We provide manned guarding, key holding and alarm response, and commercial cleaning.
- Clients. We secure The Lowry Hotel in Salford and work with Great Western Railway.
- Public sector frameworks. We hold places on the Crown Commercial Service framework (Lots 4C and 4D) and the ESPO 347_26 Security Services Framework.
- Standards. Officers are screened to BS 7858, and we hold ISO 9001 and ISO 14001, Constructionline Gold and SafeContractor accreditation.
See our security services in Manchester, security services in Stockport or read our case studies.
How to check any security company before you sign
- SIA Approved Contractor status. Search the company on the SIA’s Approved Contractor Scheme register on GOV.UK. It is voluntary, but it shows the firm has been independently assessed.
- Licensed officers. Every officer on your site needs the right SIA licence. Ask how the company checks licences and what happens if one lapses.
- BS 7858 screening. Ask whether officers are vetted to BS 7858 before they start.
- Insurance. Ask for public liability and employer’s liability certificates and check the cover suits your site.
- Supervision and reporting. Agree who supervises your officers, how often they visit and how incidents are reported to you.
- Contract terms. Check notice periods, minimum hours, pricing for extra cover and how rates change.
- References. Ask for references from clients with sites like yours, and read recent reviews.
Frequently asked questions
What are the top 10 security companies in the UK?
By UK security revenue in Infologue’s 2025 ranking, the top 10 are Mitie, Allied Universal/G4S, OCS Group UK, Securitas, Bidvest Noonan, CIS Security, Kingdom, ICTS (UK), Wilson James and ASEL.
Which is the biggest security company in the UK?
Mitie, with £1,179m of UK security revenue in Infologue’s 2025 list, followed by Allied Universal/G4S at £710m.
Is G4S still operating in the UK?
Yes. Allied Universal completed its takeover of G4S in 2021, and the business now operates as part of Allied Universal. Infologue lists them together as Allied Universal/G4S.
Are bigger security companies better?
Not always. Large firms offer national coverage and depth, which suits multi-site contracts. Regional specialists can offer closer supervision, faster local response and direct access to managers. Choose on fit, checks and references rather than size alone.
How do I check a security company is approved?
Search the company on the SIA Approved Contractor Scheme register, ask for proof that every officer holds the right SIA licence, and confirm staff are screened to BS 7858 and the company holds suitable insurance.
Who are the top security companies in Manchester?
See our separate guide to the top 10 security companies in Manchester, which lists local firms, what each is known for and who they suit.
Need security in the North West?
Tell us about your site and we will send a clear written quote, with the checks above answered up front.