Thameslink, Southern and Great Northern franchise

Thameslink, Southern and Great Northern (TSGN) is a management contract for the provision of passenger services on the Thameslink and Great Northern routes to Bedford, Luton, Peterborough, King's Lynn, Cambridge, London King's Cross, London Moorgate, Sutton, Wimbledon and Brighton, as well as the whole Southern network (including the Gatwick Express). It has been operated by the UK government since 31 May 2026 through the DfTO's wholly owned subsidiary, Greater Thameslink Railway. It will be absorbed into Great British Railways following its legal incorporation.

Until 31 May 2026, the TSGN franchise was operated by Govia Thameslink Railway, owned by Govia, and was the largest railway franchise in the United Kingdom. As of March 2025, the operator employed 7,453 staff and managed 236 stations on a 1,149 km (714 mi) network, which provided 298million annual passenger journeys.