London Overground has shortlisted four bidders that could become the new operators of its services. 

A series of improvements are expected to be made following the appointment of the new operator. Additional walk-through air-conditioned trains, more frequent services and modernised stations are among the developments expected to be made. 

Transport for London also confirmed that frequency on the North London line will be boosted by 25 per cent - an increase from eight trains per hour to ten. 

The four bidders that have been shortlisted to run London Overground from November 2016 are Arriva Rail London, LoKeGo - a joint venture between Keolis and Go-Ahead Holding - Metroline Rail, and the MTR Corporation. 

Managing director of London Rail Mike Brown said: "The new operator will play a key role in continuing that success and introducing further improvements including new air-conditioned trains."