| Name | Company Number | Date Appointed | Rating |
|---|---|---|---|
| ALLWOOD BUSINESS SOLUTIONS UK LTD | 06922863 | 03/06/2009 | Dissolved |
| CHRIS ALLWOOD LTD | 11788750 | 25/01/2019 | Silver |
| Haironville (U K) Ltd | 01688836 | 05/07/2004 | Dissolved |
| THE SLATE ECOLOGY COMPANY LIMITED | 03218483 | 06/02/2012 | Dissolved |
| Name | Company Number | Date Appointed | Date Resigned | Rating |
|---|---|---|---|---|
| ALFRED MCALPINE SLATE PENRHYN LIMITED | 00498810 | 06/02/2012 | 20/04/2018 | Gold |
| ARCELOR CONSTRUCTION UK LTD | 01688837 | 05/07/2004 | 05/06/2009 | Dissolved |
| COCKLEBANK CONSERVATIONS LIMITED | 00909873 | 06/02/2012 | 20/04/2018 | Gold |
| CWMORTHIN SLATE QUARRY 1994 COMPANY LIMITED | 02923291 | 06/02/2012 | 20/04/2018 | Gold |
| CWT-Y-BUGAIL SLATE QUARRIES,LIMITED(THE) | 00193925 | 06/02/2012 | 20/04/2018 | Gold |
| METAL CLADDING AND ROOFING MANUFACTURERS' ASSOCIATION LIMITED | 02502395 | 31/05/2004 | 08/06/2011 | Gold |
| UK STONE DIRECT LIMITED | 10794529 | 18/07/2017 | 30/11/2018 | Amber |
| WELSH SLATE LIMITED | 06391123 | 06/02/2012 | 20/04/2018 | Gold |