Answer from Hansard

The Parliamentary Under-Secretary of State for Transport (Simon Lightwood)

Rail services in Sutton and Cheam are supported by requirements on train operators to plan services and timetables to meet current and future passenger demand, ensuring value for money for the taxpayer. Govia Thameslink Railway and South Western Railway are required to work collaboratively with the Department for Transport to develop future plans, and our Department holds them accountable for delivering for passengers.