Much of the land for the railway's alignment had originally been bought by the W&ER in the 19th century, but it had not been able to raise the capital to fund the construction and its power's had expired in 1911. The Underground Group had bought the W&ER in 1922. The Underground's scheme modified the W&ER's plan to connect to the LNER branch by starting the extension from the Morden-Edgware Line station instead. The scheme involved the closure of the LNER station 200 metres south of the Underground station and retained the W&ER's connection to the LNER's single track line from where it passed over the Underground's tracks just to the east of the station and into new platforms to be built in the Underground station.