A new map from Transport for London A new map from Transport for London (Map Courtesy of Kingston Guardian) shows how south London stations could become part of the overground system if it takes control of trains in the southern area of the capital.

Mayor Sadiq Khan has already suggested routes operated by private companies such as Southern, Southeastern and South West Trains could well come under a suburban network as part of an expanded London overground and he is preparing a business case to back his plan for the government to consider.

In January, TfL announced plans, in conjunction with the Department of Transport, to incorporate metro train routes under the TfL banner as the private franchises expire, the first being Southeastern in 2018, with a view to operating all services by 2021. Although there have been calls for underperforming networks like Southern to lose their franchise sooner.

Stations currently on the troubled Southern route which could become part of TfL include East Croydon, Sutton and Wimbledon whilst South West routes which call at places like Surbiton, New Malden and Kingston could also come under the organisation's auspices as would Southeastern routes around Bromley, Bexley, Lewisham and Greenwich.

The routes would be colour coded orange in keeping with the London overground services currently operated by TfL.

The proposal has been designed to ensure London's rail network can deliver for a rising population, currently 8.6 million but expected to hit 10 million by 2030 (London Rail Network).

As well as improving the daily commute, Mr Khan believes a 'modernised suburban rail network could also unlock new homes and provide other substantial other economic benefits for London'.