London’s entire suburban railway network will be handed to Transport for London to be run by the capital’s Mayor, it has been announced.

TfL currently runs the Tube network and London Overground services, but the capital’s extensive above-ground rail network has long been under the control of a patchwork of competing private franchises.

Under the new plan, all suburban lines in the capital will be integrated into TfL’s Overground network as their current franchises expire, the city’s Evening Standard reports.

The change will see the Southeastern franchise taken over as early as 2018, with Thameslink, Great Northern, and Southern put under public control in 2021.

The newspaper says the timing of the incorporation of the South West Trains is currently under negotiation but that it could be handed to the Mayor as early as 2019.

The reorganisation will see TfL control services as far afield as Sevenoaks, Epsom, Chessington, and Hertford.

Passengers are expected to benefit from more frequent trains, improved staffing at stations, newer trains, TfL zone fares, and environmental improvements to stations.

When the Mayor took over the London Overground in 2007 similar improvements led to a six-fold increase in passenger ridership and sky-high passenger satisfaction ratings.

TfL could be slower to improve the new services than in the past because its budget is under extreme pressure, however.

The Government has announced its intentions to phase out the organisation’s funding grant and have it rely entirely on the income its raises from fares and property.

London's existing rail and tube services together on a map (TfL)

Passenger groups, TfL, and politicians of all parties in London have long campaigns for the lines to be brought under control of the capital.

The move has long been blocked by local councils just outside London, however. Kent County Council in particular previously said it was worried that long-distance commuters could lose out if stopping services were prioritised over fast regional trains.

The local authority recently dropped its opposition to the plan, however, on the basis of assurances that Kent commuters wouldn’t lose out.

The reorganisation could also herald a redesign of London’s iconic Tube map, which has struggled to legibly accommodate even the new London Overground lines it has already acquired.

Conservative candidate for London Mayor Zac Goldsmith said he “strongly welcome[d]” the news, while Labour candidate Sadiq Khan said the change was “a small step in the right direction” but called for the process to be sped up.

Mayor of London Boris John told the Evening Standard: “Our railways have been the workhorse of the London and South East economy since Victorian times.

“They're key to the day to day lives of millions of people and vital to our future prosperity, and that's exactly why this new partnership is such a seminal moment.