| WSP | London, Basingstoke, None | 41 | 132 |
| Atkins | London, Epsom, Epsom and Ewell | 16 | 128 |
| Arup | London, North East, None | 27 | 79 |
| AECOM | London, Newcastle upon Tyne, Nottingham | 14 | 137 |
| Jacobs | London, Wokingham, Berkshire | 14 | 62 |
| Colas | Crawley, Derby, Slough | 6 | 28 |
| Costain | Maidenhead, London, Worle | 14 | 14 |
| Arcadis | London, Manchester, Lomdon | 10 | 79 |
| Lanes Group | Leeds, Sutton Coldfield, Birmingham | 8 | 10 |
| Ibi Group | Manchester, Didsbury | 4 | 3 |
| Turner & Townsend | Leeds, North Lincolnshire, London | 16 | 39 |
| Futran | London, Wokingham, None | 15 | 15 |
| Ove Arup & Partners | Newcastle upon Tyne, London, None | 9 | 72 |
| Mott Macdonald | Croydon, Birmingham, London | 8 | 60 |
| Carnell Support Services | Penkridge, Staffs, Birmingham | 7 | 7 |
| AECOM Infrastructure & Environment | Chesterfield, Nottingham, Chesterfleild | 6 | 30 |
| Amey OW | London | 5 | 13 |
| Lucion Environmental | Gateshead, Hessle, Lutterworth | 4 | 12 |
| Carnell Support Service | Penkridge, Staffs, Leeds | 4 | 3 |
| Infra | Middleton | 4 | 4 |
| Deloitte | London, Altro | 3 | 122 |
| Connect Archaeology | Musselburgh, East Lothian | 3 | 3 |
| Atkins Jacobs | London | 9 | 11 |
| Corderoy | London, Birmingham | 9 | 3 |
| Atkins Jacobs Joint Venture | London, Epsom and Ewell | 8 | 8 |
| Netcompany | London | 7 | 6 |
| Morgan Sindall Construction & Infrastructure | Rugby, London | 5 | 11 |
| Compass Minerals | Winsford, Cheshire West and Chester | 4 | 11 |
| TRL | Wokingham | 4 | 23 |
| Quantum Geotechnic | Llanelli, Llandysul | 4 | 4 |
| Tarmac Trading | Alfreton | 3 | 42 |
| Volkerlaser | Worcester, Derby | 3 | 9 |
| 40Seven | Leeds | 3 | 5 |
| Archaeological Management Solutions | Kilrush | 3 | 3 |
| DDC Engineering Solutions | Wolverhampton, South Staffordshire | 3 | 3 |
| Museum of London Archaeology | London | 3 | 3 |
| Orange Partnership | Kenilworth | 3 | 3 |
| PA Consulting Services | London, Westminster | 2 | 54 |
| Faithful & Gould | Epsom, None | 2 | 44 |
| Mace | London | 2 | 26 |
| Arcadis Consulting | London, York Way London | 2 | 23 |
| Ground Control | Billericay, Bradford | 2 | 10 |
| Fujitsu Services | London, Runnymede | 2 | 12 |
| Balfour Beatty Civil Engineering | London | 2 | 10 |
| Socotec | Burton upon Trent | 2 | 7 |
| Route One Infrastructure | Wakefield | 2 | 7 |
| HW Martin Safety Fencing | Leyland, Derby | 2 | 3 |
| Ajjv | London, None | 2 | 5 |
| Chevron Traffic Management | Thame, Worcester | 2 | 3 |
| Balfour Beatty Rail | Redhill, Surrey | 2 | 2 |
| HW Martin Traffic Management | Broxtowe, Derby | 2 | 2 |
| Malcolm Hughes Land Surveyors | Swansea, Manchester | 2 | 2 |
| Ab Publishing | London | 2 | 2 |
| Concrete & Corrosion Consultancy Practice | Blean, Canterbury | 2 | 2 |
| Costain Integrated Technology Solutions | Berkshire, Weston Super Mare | 2 | 2 |
| Jacobs Systra Joint Venture | Winnersh, Wokingham | 2 | 2 |
| Pavement Testing Services | Preston | 14 | 20 |
| Benchmark Estimating | Manchester | 13 | 39 |
| BJSS | Leeds | 10 | 23 |
| CH2M Hill Europe | London | 10 | 3 |
| Abuss | Huncote | 9 | 5 |
| Amelio Group | Gloucester | 8 | 9 |
| Electronic Terminations | Woodbridge | 6 | 5 |
| JC Peacock | Ayr | 5 | 7 |
| Kier Highways | Manchester | 4 | 11 |
| Landscope Engineering | Church Stretton | 4 | 4 |
| CH2M Hill | London | 4 | 8 |
| Navtech Radar | Wantage | 4 | 2 |
| Clearview Intelligence | Milton Keynes | 4 | 4 |
| Computacenter | Hatfield | 3 | 118 |
| ESRI | Aylesbury | 3 | 25 |
| Version 1 Solutions | Wellington Crescent | 3 | 11 |
| Dyer & Butler | Stevenage | 3 | 10 |
| Pell Frischmann | London | 3 | 7 |
| Volkerfitzpatrick | Hoddesdon | 3 | 4 |
| Henry Williams | Darlington | 3 | 4 |
| John Sisk | Warrington | 3 | 2 |
| Korn Ferry Hay Group | Townlondon | 3 | 2 |
| New Signature | London | 3 | 2 |
| Headland Archaeology | Glasgow | 3 | 3 |
| Oca | Oxford | 3 | 3 |
| LA International Computer Consultants | Stoke on Trent | 2 | 85 |
| Perfect Circle | Leicester | 2 | 23 |
| Willis | None | 2 | 15 |
| RSK Environment | Leeds | 2 | 20 |
| Kier Services | Manchester | 2 | 12 |
| FM Conway | Sevenoaks | 2 | 9 |
| Bam Nuttall | Camberley | 2 | 5 |
| NGS Gritting Services | Southampton | 2 | 5 |
| BMW | Farnborough | 2 | 4 |
| Hill & Smith | Hebburn | 2 | 4 |
| Sopra Steria | Hemel Hempstead | 2 | 4 |
| BT PLC | London | 2 | 3 |
| Samaritans | Epsom and Ewell | 2 | 3 |
| Fluor | Farnborough | 2 | 3 |
| Wessex Archaeology | Salisbury | 2 | 3 |
| Socotec Asbestos | Burton upon Trent | 2 | 2 |
| Concept Engineering Consultants | London | 2 | 3 |
| Bentley Systems | London | 2 | 3 |
| Adma Solutions | Brighton | 2 | 2 |