| Name | Company Number | Date Appointed | Rating |
|---|---|---|---|
| Conservation Imports Limited | 01605094 | 10/01/1992 | Dissolved |
| S W P Planning Supervisors Ltd. | 03091020 | 14/08/1995 | Dissolved |
| Sell Wade Conservation Consultants | 01627575 | 20/12/1991 | Dissolved |
| Sell Wade Postins Ltd | 03193761 | 02/05/1996 | Dissolved |
| Name | Company Number | Date Appointed | Date Resigned | Rating |
|---|---|---|---|---|
| INVESTMENT PROPERTIES (LUTON) LIMITED | 00453038 | 12/01/1992 | 30/05/2024 | Silver |
| NATIONAL TRUST (ENTERPRISES) LIMITED (THE) | 01083105 | 01/01/2019 | 31/12/2020 | Amber |
| NATIONAL TRUST (RENEWABLE ENERGY) LIMITED | 08763161 | 01/01/2019 | 31/12/2020 | Bronze |
| RUSSELL SELL TRADING COMPANY LIMITED(THE) | 00545399 | 12/10/1992 | 30/05/2024 | Not Trading |
| THE HERITAGE ALLIANCE | 04577804 | 30/10/2002 | 03/12/2008 | Silver |
| THE HERITAGE INFORMATION TRUST | 04378549 | 21/02/2002 | 13/12/2006 | Dissolved |
| THE SOCIETY FOR THE PROTECTION OF ANCIENT BUILDINGS | 05743962 | 04/09/2012 | 05/10/2018 | Gold |