The infologue.com Top 20 for 2004 is as follows:
| Rank | Company Name | 2004 Turnover | Est Market Share |
| 1 | Group 4 Securicor | £343,000,000 | 15.59% |
| 2 | Reliance Security Services | £190,000,000 | 8.64% |
| 3 | Initial Security Ltd. | £132,000,000 | 6.00% |
| 4 | Chubb Security Personnel Ltd. | £108,000,000 | 4.91% |
| 5 | Securitas Security Services Ltd. | £85,000,000 | 3.86% |
| 6 | Securiplan Plc. | £77,000,000 | 3.50% |
| 7 | OCS Resolution Ltd | £73,000,000 | 3.32% |
| 8 | Mitie plc | £56,000,000 | 2.55% |
| 9 | Corps of Commissionaires | £50,000,000 | 2.27% |
| 10 | First Security (Guards) Ltd. | £47,000,000 | 2.14% |
| 12 | Vision Security Group Ltd | £42,000,000 | 1.91% |
| 11 | The Shield Guarding Co. Ltd. | £39,000,000 | 1.77% |
| 13 | Pegasus Security Ltd | £35,700,000 | 1.62% |
| 14 | Sabrewatch Ltd | £34,000,000 | 1.55% |
| 15 | ICTS UK Ltd | £33,000,000 | 1.50% |
| 16 | Wilson James Ltd. | £32,000,000 | 1.45% |
| 17 | Legion Security Plc | £29,000,000 | 1.32% |
| 18 | Temple Security Ltd. | £22,000,000 | 1.00% |
| 19 | Carlisle Facilites Services Ltd | £20,000,000 | 0.91% |
| 20 | Frances Clarke Ltd. | £18,500,000 | 0.84% |
| Estimated Annual Turnover of Top 20 Companies | £1,466,200,000 | 66.65% | |
| Estimated Annual Turnover of UK Security Guarding Industry | £2,200,000,000 | 100.00% |
The above table is based on estimates and historical published data of annual turnover and should be viewed only as a guide to the approximate size of the largest companies in the manned security industry. The turnover is calculated on an annualised basis as of end November 2004 and relates only to revenue derived from the regulated sector of the Private Security Industry. Some companies have non related areas of business in their statutory accounts which Infologue.com attempts to estimate and factor out of the estimated turnover. Whilst some companies are now providing information on turnover to Infologue.com all figures will not be accurate as statutory information can be up to two years out of date. Infologue.com welcomes input from the companies in the Infologue.com Top 20 and will amend any verified inaccuracies as soon as possible. We will not entertain new entrants to the Infologue.com Top 20 during 2004/5 unless there is a vacancy. Therefore these figures should be treated with caution and be regarded as a best guess. The Infologue.com Top 20 UK Companies in the Regulated Security Sector 2004 is an exclusive production of Infologue.com and may not be replicated without the express written permission of the producers thereof.