| Name | Company Number | Date Appointed | Rating |
|---|---|---|---|
| CELL SITE CONNECTION SERVICES LIMITED | 04566781 | 01/04/2011 | Dissolved |
| Electricity Association Ltd | 02367010 | 01/04/2000 | Dissolved |
| Hyder Utilities (Holdings) Ltd | 03405267 | 15/09/2000 | Dissolved |
| Llanishen Developments Ltd | 04302310 | 13/11/2001 | Dissolved |
| Mirant Asia-Pacific (Europe) Financial Services Ltd | 04242669 | 28/09/2001 | Dissolved |
| Mirant Asia-Pacific (Europe) Ltd | 04242673 | 28/09/2001 | Dissolved |
| Mirant Bahamas Holdings Ltd | 04252027 | 28/09/2001 | Dissolved |
| Mirant Global Finance Preferred Investments Ltd | 04251704 | 28/09/2001 | Dissolved |
| Pplg Europe Holdings Ii Ltd | 03532176 | 21/08/2003 | Dissolved |
| Revenue Protection Services Ltd | 05409455 | 31/03/2005 | Dissolved |
| SIUK FINANCE | 03861010 | 19/11/1999 | Dissolved |
| SIUK INVESTMENTS | 03861059 | 19/11/1999 | Dissolved |
| Siuk Ltd | 03073865 | 23/10/1997 | Dissolved |
| WPD FINANCE LIMITED | 04081181 | 26/09/2000 | Dissolved |
| WPD GUERNSEY LIMITED | 04066386 | 19/12/2000 | Dissolved |
| Wpd Holdings Uk | 03585938 | 18/06/1998 | Dissolved |
| Wpdh Ltd | 03053961 | 23/10/1997 | Dissolved |
| Name | Company Number | Date Appointed | Date Resigned | Rating |
|---|---|---|---|---|
| Croeso Systems Development Ltd | 02624610 | 20/04/2001 | 31/08/2004 | Dissolved |
| DWR CYMRU (HOLDINGS) LIMITED | 03954867 | 24/01/2001 | 11/05/2001 | Silver |
| DWR CYMRU CYFYNGEDIG | 02366777 | 13/12/2000 | 11/05/2001 | Amber |
| ENERGY AND UTILITY SKILLS LIMITED | 03812163 | 21/09/2005 | 10/04/2007 | Silver |
| Electricity Association Ltd | 02367010 | 11/12/1998 | 17/12/1998 | Dissolved |
| HIGHER HALWYN MANAGEMENT COMPANY LIMITED | 04393612 | 31/08/2007 | 07/11/2018 | One Red Flag |
| HIGHER HALWYN MANAGEMENT COMPANY LIMITED | 04393612 | 31/08/2007 | 07/11/2018 | One Red Flag |
| HYDER LIMITED | 02366776 | 15/09/2000 | 07/11/2018 | Dissolved |
| Hyder Overseas Investments Ltd | 02906578 | 30/03/2001 | 19/02/2002 | Dissolved |
| Hyder Securities (Utilities) Ltd | 03310618 | 15/09/2000 | 19/02/2002 | Dissolved |
| Mirant Investments Uk Ltd | 03743976 | 26/03/1999 | 31/05/1999 | Dissolved |
| NG ELECTRICITY DISTRIBUTION LIMITED | FC023442 | 12/09/2001 | 31/07/2017 | Silver |
| R SYMONS ENTERPRISES LLP | OC382330 | 11/02/2013 | 07/11/2018 | One Red Flag |