The infologue.com Top 20 for 2001 is as follows:
| Rank | Company Name | 2001 Turnover | Est Market Share |
| 1 | Securicor Guarding Ltd. | £195,000,000.00 | 8.86% |
| 2 | Group 4 Total Security Ltd. | £185,000,000.00 | 8.41% |
| 3 | Reliance Security Services Ltd. | £150,000,000.00 | 6.82% |
| 4 | Initial Security Ltd. | £115,000,000.00 | 5.23% |
| 5 | Chubb Security Personnel Ltd. | £99,000,000.00 | 4.50% |
| 6 | Securitas Security Services Ltd. | £72,000,000.00 | 3.27% |
| 7 | Securiplan Plc. | £60,000,000.00 | 2.73% |
| 8 | Capitol Security Services Ltd. | £55,000,000.00 | 2.50% |
| 9 | Corps of Commissionaires Management Ltd. | £45,000,000.00 | 2.05% |
| 10 | First Security (Guards) Ltd. | £37,000,000.00 | 1.68% |
| 11 | Galago Ltd | £34,000,000.00 | 1.55% |
| 12 | Sabrewatch Ltd | £28,000,000.00 | 1.27% |
| 13 | Legion Security Plc | £25,000,000.00 | 1.14% |
| 14 | Pegasus Security Group Ltd. | £23,500,000.00 | 1.07% |
| 15 | The Shield Guarding Co. Ltd. | £23,000,000.00 | 1.05% |
| 16 | Trident Safeguards Ltd. | £22,000,000.00 | 1.00% |
| 17 | Profile Security Services Ltd. | £18,000,000.00 | 0.82% |
| 17 | Resolution Security Ltd. | £18,000,000.00 | 0.82% |
| 19 | Wilson James Ltd. | £17,500,000.00 | 0.80% |
| 20 | Regent Security Limited | £14,000,000.00 | 0.64% |
| Estimated Annual Turnover of Top 20 Companies | £1,236,000,000 | 56.18% | |
| Estimated Annual Turnover of UK Security Industry | £2,200,000,000 |