The infologue.com Top 20 for 2003 is as follows:
| Rank | Company Name | 2003 Turnover | Est Market Share |
| 1 | Securicor Security Ltd. | £189,000,000.00 | 8.59% |
| 2 | Reliance Security Services Ltd. | £182,000,000.00 | 8.27% |
| 3 | Group 4 Total Security Ltd. | £179,000,000.00 | 8.14% |
| 4 | Initial Security Ltd. | £115,000,000.00 | 5.23% |
| 5 | Chubb Security Personnel Ltd. | £105,000,000.00 | 4.77% |
| 6 | Securiplan Plc. | £62,000,000.00 | 2.82% |
| 7 | Securitas Security Services Ltd. | £60,000,000.00 | 2.73% |
| 8 | Corps of Commissionaires Management Ltd. | £52,000,000.00 | 2.36% |
| 9 | OCS Ltd | £49,000,000.00 | 2.23% |
| 10 | First Security (Guards) Ltd. | £42,000,000.00 | 1.91% |
| 11 | Sabrewatch Ltd | £34,000,000.00 | 1.55% |
| 12 | Pegasus Security Ltd | £32,000,000.00 | 1.45% |
| 13 | The Shield Guarding Co. Ltd. | £31,000,000.00 | 1.41% |
| 14 | Wilson James Ltd. | £26,000,000.00 | 1.18% |
| 15 | Vision Security Group Ltd | £26,000,000.00 | 1.18% |
| 16 | Trident Safeguards Ltd. | £23,000,000.00 | 1.05% |
| 17 | Resolution Security Ltd. | £22,000,000.00 | 1.00% |
| 18 | Legion Security Plc | £22,000,000.00 | 1.00% |
| 19 | Temple Security Ltd. | £22,000,000.00 | 1.00% |
| 20 | ICTS UK Ltd | £21,000,000.00 | 0.95% |
| Estimated Annual Turnover of Top 20 Companies | £1,294,000,000 | 58.82% | |
| 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 2003 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on turnover to Infologue.com all figures will not be accurate as statutory information can be up to two years out of date.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 2003/4 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 2003 is an exclusive production of Infologue.com and may not be replicated without the express written permission of the producers thereof.