Prior to the name being adopted in November 2024,[1] the service was labelled in Transport for London timetables as the Richmond and Clapham Junction to Stratford route.
[2] The name was chosen to honour the Mildmay Mission Hospital, which treated victims of the HIV/AIDS crisis in the 1980s, and the line is blue on the Tube map.
[5] In July 2023, TfL announced that it would be giving each of the six London Overground services unique names by the end of 2024.
[6][7] In February 2024, it was confirmed that the service from Stratford on the North London and West London railway lines would be named the Mildmay line (to honour the Mildmay Hospital in Bethnal Green, which treated victims of the HIV/AIDS crisis in the 1980s) and would be coloured sky blue on the updated network map.
This service shares infrastructure with Mildmay line trains between Clapham Junction and Shepherd's Bush stations, after which they join the West Coast Main Line en route to Watford Junction.