| Name | Company Number | Date Appointed | Rating |
|---|---|---|---|
| CITYBUS LIMITED | NI009039 | 01/10/2021 | Silver |
| FLEXIBUS LIMITED | NI006724 | 01/10/2021 | Not Trading |
| METRONET REW LIMITED | 03211492 | 22/03/2010 | Dissolved |
| METRONET TMU LIMITED | 03211465 | 22/03/2010 | Dissolved |
| NIR NETWORKS LIMITED | NI017638 | 01/10/2021 | Not Trading |
| NIR OPERATIONS LIMITED | NI021091 | 01/10/2021 | Bronze |
| NORTHERN IRELAND RAILWAYS COMPANY LIMITED | NI006929 | 01/10/2021 | Silver |
| RAIL SAFETY AND STANDARDS BOARD LIMITED | 04655675 | 23/06/2022 | Gold |
| RESTORATION AND RENEWAL DELIVERY AUTHORITY LTD | 12559954 | 16/04/2020 | Amber |
| TRANSLINK (NI) LIMITED | NI006673 | 01/10/2021 | Not Trading |
| ULSTERBUS LIMITED | NI006725 | 01/10/2021 | Bronze |
| Name | Company Number | Date Appointed | Date Resigned | Rating |
|---|---|---|---|---|
| CROSSRAIL 2 LIMITED | 09580635 | 23/02/2016 | 10/07/2020 | Not Trading |
| DOCKLANDS LIGHT RAILWAY LIMITED | 02052677 | 01/02/2011 | 01/09/2016 | Bronze |
| HEATHROW AIRPORT LIMITED | 01991017 | 31/07/2009 | 09/03/2010 | Silver |
| HEATHROW EXPRESS OPERATING COMPANY LIMITED | 03145133 | 12/01/2009 | 09/03/2010 | Gold |
| LHR AIRPORTS LIMITED | 01970855 | 31/07/2009 | 09/03/2010 | Silver |
| LONDON & PARTNERS LIMITED | 07493460 | 16/05/2017 | 30/06/2020 | Amber |
| LONDON UNDERGROUND LIMITED | 01900907 | 08/01/2001 | 31/07/2008 | Bronze |
| LUL NOMINEE BCV LIMITED | 06221959 | 22/03/2010 | 01/09/2016 | Not Trading |
| LUL NOMINEE SSL LIMITED | 06242508 | 22/03/2010 | 01/09/2016 | Not Trading |
| NSAR LIMITED | 07484465 | 01/12/2016 | 23/06/2020 | Bronze |
| RAIL FOR LONDON LIMITED | 05965930 | 01/02/2011 | 01/09/2016 | Bronze |
| TRAMTRACK CROYDON LIMITED | 03092613 | 01/02/2011 | 01/09/2016 | Amber |
| TRANSPORT TRADING LIMITED | 03914810 | 24/03/2010 | 10/07/2020 | Silver |
| TUBE LINES LIMITED | 03923425 | 27/06/2010 | 01/09/2016 | Bronze |