would take over services on the Hounslow and Uxbridge branches. The line, being still single-tracked, was doubled in stages. Works were completed on 27 November 1926, with the station's alignment reconfigured to have three platforms and brought into use on 11 December. The oldest platform furthest to the south was not reopened until 27 March 1927, with the original station still in situ. Between 1930 and 1931, a new station building was constructed facing onto Bath Road to replace the original building which was parallel with the tracks and set back at an angle from the road. The original building was gradually demolished, and the new building opened on 5 July 1931. Piccadilly line services, which had been running as far as Northfields since 9 January 1933, were extended to Hounslow West on 13 March 1933. From that date, the branch was jointly operated by both lines. District line services were progressively reduced to rush-hour only services in the late 1950s; they were withdrawn on 9 October 1964. Heathrow extension An extension of the line from Hounslow West to serve Heathrow Airport had been planned since the 1960s. Formal approval was given in 1967, and work began with a groundbreaking ceremony by Sir Desmond Plummer on 27 April 1971. The original alignment of the tracks and platforms at Hounslow West was too skewed from the extension. The new alignment was to relocate the station platforms underground, with cut and cover tunnels along Bath Road and Great South West Road. The line surfaces briefly over the River Crane before descending to reach Hatton Cross towards Heathrow. The new rerouted tracks meant that the existing had to be reduced to single track operation until the station approach. Platform 3, being the northernmost, was decommissioned early on 22 October 1971 due to being situated right on the path of the new track alignment. The old DR signal box was also taken out of service, with a temporary one built near Platform 1. Some of the tracks were demolished in June 1975 for further excavation and track simplification works. The new platforms were brought into use on 14 July 1975 and the line was opened as far as Hatton Cross five days later on 19 July. The existing 1930s station building was kept, and a new link was constructed to connect to the new platforms. The line was further extended to Heathrow on 16