Suggestion: any sub surface LU line (Metropolitan, Circle, H&C, District) set during the time of S Stock rollout so if it's the Circle or H&C then we get S and C Stock. Also, if only one is done then AI could operate the services on the other lines sharing tracks. For example, if the District line is created, then AI Circle line trains can operate between Gloucester Road and Tower Hill and AI H&C trains between Aldgate East and Barking. This could make a great Rush Hour style route and provide lots of variety. Stations on SSR: Met line: Aldgate to Uxbridge, Watford, Amersham and Chesham. Circle line: Hammersmith around to Edgware Road via High Street Kensington, Victoria and Aldgate with Inner and Outer Circles. District line: Upminster to Olympia, Ealing Broadway, Richmond and Wimbledon. H&C line: Barking to Hammersmith via King's X.
