In 1997 a new bespoke depot was constructed at the southern end of the site, between the Great Western depot and the main line, funded by the British Airports Authority to service and maintain the Heathrow Express and Heathrow Connect service trains. This was the first new privately funded train depot in the UK since the British railways nationalisation in 1948. The inauguration of the Heathrow Express services saw the electrification of the GWML from Paddington to Hayes and onto Heathrow Airport using 25 kV overhead catenary.