| WSP | London, City of London, Basingstoke | 162 | 132 |
| WSP Safety | Newark, Newark on Trent | 6 | 6 |
| WSP Development & Transportation | Exeter | 2 | 2 |
| WSP Cel | Coventry | 1 | 1 |
| WSP Parsons Brinckerhoff | London | 1 | 1 |
| AECOM | London, St Albans, Leeds | 25 | 137 |
| Atkins | Epsom, Surrey, Cardiff | 23 | 128 |
| Mott Macdonald | Croydon, Cardiff, Edinburgh | 20 | 60 |
| Stantec | High Wycombe, Reading, Bristol | 20 | 15 |
| Jacobs | Wokingham, London, Cardiff | 16 | 62 |
| Sweco | Leeds, Glasgow, London | 14 | 5 |
| Arcadis Consulting | London, Cardiff, York | 15 | 23 |
| Ove Arup & Partners | London, Cardiff, Sheffield | 13 | 72 |
| Currie & Brown | London, Edinburgh, Eurocentral | 11 | 29 |
| Turner & Townsend Project Management | Leeds, Glasgow, Edinburgh | 9 | 13 |
| Wardell Armstrong | Stoke on Trent, Cardiff, Staffordshire | 10 | 17 |
| Systra | London, Glasgow, Liverpool | 7 | 13 |
| Capita Property & Infrastructure | Cardiff, London, Bristol | 8 | 21 |
| Mace | London, Manchester | 7 | 26 |
| Environment Partnership | Warrington | 6 | 8 |
| Faithful Gould | Epsom, Glasgow, Leeds | 9 | 44 |
| Rider Levett Bucknall | Birmingham, Manchester | 9 | 21 |
| Ridge & Partners | Woodstock, Liverpool, Manchester | 8 | 38 |
| RSK Environment | Coventry, Helsby, Glasgow | 5 | 20 |
| Hoare Lea | Bristol | 5 | 10 |
| Pell Frischmann Consultants | Wakefield, London, Westminster | 5 | 9 |
| CPC Project Services | London | 4 | 16 |
| Tetra TECH | Leeds, Cardiff | 9 | 9 |
| Pick Everard | Leicester, Glasgow, Inverness | 8 | 16 |
| Savills | London, Westminster | 6 | 30 |
| Costain | Maidenhead, Manchester, Cardiff | 6 | 14 |
| KPMG | London | 5 | 102 |
| Turner & Townsend | Manchester, Birmingham | 5 | 39 |
| Avison Young | Birmingham | 5 | 12 |
| Amey OW | London, Oxfordshire | 5 | 13 |
| RG P | Leicester | 5 | 7 |
| Hilson Moran Partnership | Farnborough, Hampshire | 5 | 10 |
| Ahr Architects | Manchester, Glasgow, London | 5 | 5 |
| Pricewaterhousecoopers | London | 4 | 75 |
| Arcadis | Edinburgh, Lomdon, Manchester | 4 | 79 |
| Ramboll | London | 4 | 20 |
| Apem | Stockport, None | 4 | 13 |
| BDP | Bristol, Manchester, London | 4 | 13 |
| Mott Macdonald Main Account | Cardiff | 4 | 4 |
| AECOM Infrastructure & Environment | London, Basingstoke | 3 | 30 |
| Steer Davies & Gleave | London | 3 | 28 |
| Steer | London | 3 | 4 |
| Nationwide Data Collection | Warwick, Ossett | 3 | 4 |
| Curtins Consulting | Liverpool, Cardiff | 6 | 16 |
| Robinson Low Francis | London, Glasgow | 6 | 14 |
| Cushman & Wakefield Debenham Tie Leung | London | 5 | 9 |
| Gleeds Cost Management | London | 5 | 5 |
| Ernst & Young | London | 4 | 89 |
| RPS Consulting Services | Abingdon | 4 | 23 |
| Jeremy Benn Associates | Newport, Edinburgh | 4 | 8 |
| Appleyard & Trew | Manchester | 4 | 3 |
| Axis M&E Consulting Engineers | Nottingham | 4 | 4 |
| Local Transport Projects | Beverley | 4 | 4 |
| Deloitte | London | 3 | 122 |
| PA Consulting Services | London | 3 | 54 |
| Grant Thornton | London | 3 | 38 |
| Calfordseaden | London, Bromley | 3 | 20 |
| Waterman Infrastructure & Environment | Perth, Birmingham | 3 | 16 |
| Hydrock Consultants | Bristol | 3 | 11 |
| BWB Consulting | Nottingham | 3 | 10 |
| Stace | Epping, Epping Forest | 3 | 7 |
| Ibi Group | Didsbury, Birmingham | 3 | 3 |
| Stride Treglown | Cardiff, Clifton Down Bristol | 3 | 3 |
| Gleeds | Edinburgh, North Tyneside | 3 | 3 |
| Gattica Associates | Southsea | 3 | 2 |
| Intelligent Data Collection | Maidenhead, Windsor and Maidenhead | 3 | 2 |
| Collaborative Project Management Services | Cardiff, London | 3 | 3 |
| Cotswold Archaeology | Cirencester, Milton Keynes | 3 | 3 |
| Premier Energy Services | Billingshurst, West Sussex | 3 | 3 |
| Reach Active | Hertford, Middlesex | 3 | 3 |
| SMS Energy Services | Pontprennau, Cardiff | 3 | 3 |
| Ward Williams Associates | Truro, Cornwall | 3 | 3 |
| Welling Partnership Property & Construction Consultants | Southampton | 3 | 3 |
| Frazer Nash Consultancy | Dorking, Bristol | 2 | 32 |
| Ricardo AEA | Harwell, None | 2 | 22 |
| Hawkins Brown Design | London | 2 | 7 |
| Balfour Beatty Civil Engineering | London | 2 | 10 |
| Arup | London | 2 | 79 |
| Jacobs Clean Energy | London | 2 | 11 |
| Ecs Consultants | Cheadle, Cheshire | 2 | 6 |
| London Economics | London | 2 | 4 |
| Singleton Clamp & Partners | Manchester | 2 | 5 |
| Temple Group | West Sussex, London | 2 | 3 |
| Economic Consulting Associates | London | 2 | 4 |
| Integrated Transport Planning | Nottingham, Birmingham | 2 | 3 |
| Si Sealy & Associates | Stockport | 2 | 3 |
| Wilde Consultants | Cheshire, Stockport | 2 | 3 |
| Air Quality Consultants | Bristol | 2 | 2 |
| Ricardo Energy & Environment | Oxon, West Sussex | 2 | 2 |
| Eastwood & Partners Consulting Engineers | Sheffield | 2 | 2 |
| Sia Partners | London | 2 | 2 |
| TWC Consulting | Aintree | 2 | 2 |
| Betts Associates | Flintshire, Sealand | 2 | 2 |
| Binnies | Redhill | 2 | 2 |
| First Economics | London | 2 | 2 |