| Name | Company Number | Date Appointed | Rating |
|---|---|---|---|
| COMPLIANT COMPREHENSIVE COMPETITIVE PROJECTS LIMITED | 10742099 | 26/04/2017 | Dissolved |
| CTL SEAL LIMITED | 06837452 | 05/03/2009 | Gold |
| DIAMOND DESIGN SERVICES LIMITED | 13690978 | 20/10/2021 | Not Trading |
| DIAMOND ENGINEERING GROUP LTD | 13265999 | 15/03/2021 | Silver |
| DIAMOND ENGINEERING SERVICES LIMITED | 10795994 | 31/05/2017 | Gold |
| DIAMOND RAIL GROUP LIMITED | 11019392 | 18/10/2017 | Gold |
| DIAMOND RAIL SERVICES (UK) LIMITED | 07364847 | 03/09/2010 | Silver |
| DIAMOND RESPONSIVE ENGINEERING LIMITED | 10051798 | 09/03/2016 | Gold |
| HLW 207 LIMITED | 04829177 | 17/01/2005 | Gold |
| L AND A INDUSTRY LIMITED | 09997854 | 10/03/2016 | Bronze |
| L ENGLAND & A ENGLAND LIMITED | 03596042 | 09/07/1998 | Bronze |
| NICHE ENGINEERING LIMITED | 09784186 | 30/05/2017 | Dissolved |
| RESPONSIVE HOLDINGS LTD | 12615215 | 20/05/2020 | Not Trading |
| TFL RESPONSIVE ENGINEERING LIMITED | 05927511 | 02/03/2009 | Gold |
| THE STANDARD STEAM LOCOMOTIVE COMPANY LIMITED | 03192444 | 27/02/2020 | Gold |
| Name | Company Number | Date Appointed | Date Resigned | Rating |
|---|---|---|---|---|
| ASSURED EQUITY FINANCE LTD | 12618494 | 22/05/2020 | 12/06/2020 | Bronze |