The service was launched on 12 June 2005 and ceased on 19 May 2018, when it was absorbed into the TfL Rail concession, in advance of becoming part of the Elizabeth line once it opened on 24 May 2022.

[7] In May 2022, TfL Rail services were rebranded as the Elizabeth line, with through trains running through central London from November 2022.

Oyster cards, Travelcards and Freedom Passes were not valid between Hayes & Harlington and Heathrow, but could be used throughout the rest of the route.

[10] The service was designed principally for the use of airport staff and West London residents for travel to Heathrow or Paddington.

As part of the original Heathrow Express project, these lines were electrified at 25 kV AC overhead as a diversionary route, and featured Automatic Train Protection.

An additional flyover bridge was built in 2008 as part of Crossrail works to enable trains to enter or leave the airport spur without crossing any of the Great Western Main Line tracks.

[12][13] The service pattern, as of October 2016[update], was as follows: Heathrow Connect used five-car Class 360/2 electric multiple units.

One was brought to Northampton Kings Heath Siemens Depot in 2002 before South West Trains' Class 450s were delivered.

[19][20] On 20 May 2018, TfL Rail took over the services operated by Heathrow Connect as a precursor to the full opening of the Elizabeth line,[21][22] which at that time was expected to take place in December 2018.