A new map has been unveiled showing what south London’s train network could look like if services were taken under the control of Transport for London (TfL).

Routes currently operated by private companies including Southern, Southeastern and South West Trains are swathed in orange on the new map, which has been released as Mayor Sadiq Khan prepares to formally present the business case for bringing suburban services into an expanded London Overground network.

In January TfL announced plans to take control of metro train routes in the capital as private franchises expire, with the aim of operating all services by 2021.

But commuters and politicians, including Mr Khan, have backed calls for underperforming networks like Southern to be stripped of their franchise earlier if service does not improve.

Mr Khan, who will present the business case for the TfL takeover to the government over the next month, said: “Passengers on London’s suburban rail routes simply aren’t getting a good enough service.

Surrey Comet:

"They face increasing rail fares year after year, yet face daily delays, cancellations and overcrowding.

“The government has already agreed that devolving rail services would improve the daily commute for millions of Londoners.

"Ahead of the Autumn Statement, I’m looking forward to presenting the full business case for how a transformed and modernised suburban rail network could also unlock new homes and provide other substantial other economic benefits for London.”

Last month transport secretary Chris Grayling rejected an offer from Mr Khan to stage an emergency takeover of the struggling Southern network, which has been beset by cancellations, delays and industrial action since earlier this year.

Shortly afterwards Mr Grayling announced a £20m cash injection to allow Southern to “get to grips” with the problems – just 24 hours before the franchise’s owner announced year-end profits of nearly £100m.

The map unveiled by TfL this week sees busy stations served by Southern services, such as East Croydon, Sutton, and Wimbledon, absorbed into the newly expanded London Overground network.

Routes operated by South West Trains serving station including Surbiton, New Malden and Kingston would be placed under TfL control.

The same would apply to Southeastern services around Bromley, Bexley, Lewisham and Greenwich.

Mr Khan added: “As our new TfL map demonstrates, devolution will help us deliver a truly integrated transport network where rail passengers get the same standard of service and reliability they get on the tube, allowing people to connect quickly with all parts of inner and outer London.”

Latest on-time train performance on London Overground services was 94.7 per cent, according to TfL 77.3 per cent on Thameslink and 79.5 per cent on Southern trains.