| Name | Company Number | Date Appointed | Rating |
|---|
| Name | Company Number | Date Appointed | Date Resigned | Rating |
|---|---|---|---|---|
| SIR ROBERT MCALPINE (HOLDINGS) LIMITED | 02754943 | 31/07/2017 | 24/04/2019 | Bronze |
| SIR ROBERT MCALPINE LIMITED | 00566823 | 31/07/2017 | 16/02/2024 | Bronze |
| TETRA TECH GROUP LIMITED | 06595608 | 01/07/2008 | 09/06/2017 | Amber |
| TETRA TECH INTERNATIONAL DEVELOPMENT PROJECTS LIMITED | 03195423 | 27/10/2009 | 09/06/2017 | Silver |
| TETRA TECH UK CONSULTING GROUP LIMITED | 01869543 | 01/07/2008 | 09/06/2017 | Silver |
| WYG INTERNATIONAL LIMITED | 03195485 | 01/07/2008 | 18/04/2017 | Dissolved |