In 1990, a heavy repair shop was built at the southern end of the depot, but this function was transferred back to Acton Works, and the building is now used for storage of artefacts for the London Transport Museum.

Access to the depot by rail can be gained from both tracks at Ealing Common station, where the junction is to the south of the platforms.

At the southern end of the depot, a steep incline leads down to the two eastbound platforms at Acton Town station.

[1] When they took over the running of their own trains, rather than allowing the Metropolitan Railway to provide this service, they built a depot for their new rolling stock at Lillie Bridge, to the west of Earl's Court.

[7] Mill Hill Park was also the name of Acton Town station, prior to a reorganisation of the tracks near the depot in 1910, which created a flying junction so that there was no conflict between westbound trains moving from Acton Town towards Ealing Broadway and movements on the line to South Ealing and Northfields.

[8] The depot is accessible from both ends, and lies in a north-west to south-east orientation, on the north-east side of the tracks between Ealing Common and Acton Town stations.

The basic layout has remained much the same since its opening, with nine stabling sidings next to the running lines, and a car shed with another 11 tracks beyond those.

They were all delivered to Mill Hill Park Works, where the Sprague-Thomson-Houston electro-magnetic control equipment was fitted, and enough vehicles were ready for the first electric service to start on 13 June 1905, running between South Acton and Hounslow, while electric trains ran from Whitechapel to Ealing Broadway for the first time on 1 July.

On reaching the terminal station, there was insufficient air to apply the brakes, and it hit the buffer stops, killing one of the crew.

The incident led to the fitting of a control governor to all trains on the Underground, which prevented forward motion unless there was sufficient air to apply the brakes.

[16] D Stock trains were transferred to the museum yard via Ealing Common Depot, and were then loaded onto low-loader trucks to be taken away for refurbishment.

The pair were numbered L30 and L31, and were stabled at Lillie Bridge Depot, where they were used for shunting, but also ran stores trains from there to Ealing Common regularly.

This was delivered to Ruislip depot, in a state where it was nearly ready for service, but final commissioning occurred at Ealing Common, and the vehicles could not be driven under their own power until this was done.

The pilot motor cars were used in pairs, one at each end of the train being transferred, and carried large stencils to indicate that they were not for scrapping.

[24] In recent years, the number of trains stored at the depot in order to provide the timetabled levels of service has increased.