In the 1890s, the Metropolitan District Railway, which later became the District Line but was operating as an independent company at the time, recognised the inadequate service to Uxbridge and Harrow. To address this, they proposed the construction of a railway line towards both towns, and this led to the formation of the Ealing & South Harrow Railway. The railway line was intended to extend to South Harrow, which was then a rural area located to the south of Roxeth.

Construction of the railway line was completed by 1899, but the District Line faced financial difficulties that delayed its opening until 1903. Consequently, South Harrow became the terminus of a line extending from Park Royal & Twyford Abbey. The location around Northolt Road subsequently developed into South Harrow’s own commercial and residential hub.

The original station building was approximately 170 metres south of the present-day station. This extension marked a significant milestone in the Underground’s history, as it was the first surface line to be electrified. On 1 March 1910, the line was further extended to the north to connect with the tracks of the Metropolitan Railway at Rayners Lane, enabling services to reach Uxbridge. The viaduct spanning the Roxeth Marsh, located between South Harrow and Rayners Lane, was an impressive engineering achievement of its time.

In 1932, the District Line service to South Harrow was replaced by the Piccadilly Line. However, it’s worth noting that the District Line continued operating from South Harrow north to Uxbridge until the following year.

On 5 July 1935, a new station designed by Charles Holden was opened on Northolt Road.