The southernmost point of the Dudding Hill line is in Acton, where it branches north from the North London Line between Acton Central and Willesden Junction stations, immediately to the west of the site of the proposed Old Oak Common High Speed 2 station.

From there it heads north then east, passing through Gladstone Park and terminating at a triangular junction with the Midland Main Line between Cricklewood and Hendon.

[3] It had stations at Dudding Hill and Harlesden (the latter also called Harrow Road and Stonebridge Park).

From 1878 to 1880[3] it formed the basis of the Midland Railway's Super Outer Circle, which ran from St Pancras to Earl's Court via Cricklewood, Acton and the District line.

summer special trains were run on the Dudding Hill Line, to carry holidaymakers from the Midlands to south coast holiday resorts.

Later plans replaced all this with a new tunnel connection,[9] and finally the Aylesbury branch was dropped completely from the scheme.

[10] During the late 1990s, BAA planned to run some or possibly all Heathrow Express trains along the line to St.

[15] After several independent efforts, in early 2009 the British Government began an official detailed study of possible high-speed rail routes.

This involves a major development area for London, based around a new Old Oak Common station for High Speed 2 and Great Western Main Line, including Crossrail.

In October 2016, a report by Jonathan Manns and Dr Nicholas Falk, on behalf of the UK Government's All Party Parliamentary Group for London's Planning and Built Environment, proposed new orbital rail links in West London modelled on Swift Rail or Rapid Transit, connecting existing communities and those which could accommodate additional growth.

[17] It was agreed at the following meeting of the West London Economic Prosperity Board, in December 2016, to undertake further analysis on the feasibility of establishing an orbital passenger rail connecting regeneration schemes.