Subsequently, Acton continued to overhaul major items after they had been removed from trains at the depots, and tendered for work, which included the conversion of the A60 Stock to One Person Operation.

It is likely to be reorganised and expanded to house the departments displaced from Lillie Bridge Depot which is being demolished as part of the redevelopment of Earls Court Exhibition Centre.

Major rolling stock projects carried out at the works have included the refurbishment of 15 of the Metropolitan Railway electric locomotives in 1953, and the conversion of the experimental 1960 Stock for Automatic Train Operation trials on the Woodford to Hainault section of the Central line, in preparation for its use on the Victoria line.

Maintenance of Metropolitan line trains moved from Neasden Depot to Acton Works in 1933, when the London Passenger Transport Board was formed.

Dirt and accumulated debris was removed by high-pressure air jets, before insulation testing of the electrical circuits was carried out.

In 1961, a lathe was installed at Northfields depot which could reprofile the whole wheel, without uncoupling individual cars, and this became standard practice.

By 1985, much of the equipment at Acton needed replacing, and London Underground took the decision to devolve the overhaul of cars to the depots on each line.

The following year, a Depot Engineering Support Unit (DESU) opened at Ealing Common Depot, located on sidings at its eastern end, but this was short-lived, and the functions of the Support Unit were relocated back to Acton Works soon afterwards, with the building at Ealing Common being used to store items from the London Transport Museum's collection.

[2] London Underground have been looking at options for Lillie Bridge Depot since 2010, as it is due to be redeveloped as part of the Earls Court Exhibition Centre site, and have decided that most of the workshops can be moved to Acton.

[11] From its beginning, Acton Works had been the responsibility of William Sebastian Graff-Baker, who had been born in England in 1889 to American parents.

[14] During the Second World War, many of the engineers at Acton were granted 'reserved occupation' status, which meant that they were not called up to serve in the armed forces.

[15] London Transport had built numbers of Halifax bombers during the war, and so had gained experience with duraluminium panels.

This was put to use in the design of the R Stock, built to replace trains with manually operated doors on the Circle and District lines.

A 1938 Stock driving motor car was remodelled at Acton in 1949, with windows and the glazing of the doors carried upwards into the roof.

Prior to the re-equipping of the Piccadilly line, a full scale mockup of half of a car of 1952 Stock was produced at Acton, incorporating the new glazing and other features.

[17] By the mid-1960s, Acton's Rolling Stock Design Office had a new head, in Stan Driver, who had cultivated a good working relationship with Misha Black and James Williamns.

They worked on the concepts and general arrangements for the interior of the 1967 Stock, while Acton concentrated on the engineering aspects of the design.

[18] The 1973 Stock designed for the Piccadilly line at the time of the Heathrow extension, was another collaboration between the Acton team and the Design Research Unit, and the elegant lines and attention to detail of the finished trains was highly praised by Martin Pawley, the architectural commentator for the Architects' Journal, in the April 1987 edition.

[19] The Design Research Unit had been excluded from working on the interior, which showed no fresh concepts, and the provision for luggage for travellers to the airport was poorly thought out.

The second batch was built in 1912 by the Metropolitan Amalgamated Railway Carriage and Wagon Company, and consisted of 22 motor cars and eight trailers, known as D Stock.

The work involved constructing a drivers cab at the trailing end, and fitting duplicate brake cylinders and triple valves.

Acton converted the cars in pairs, one receiving the rotary transformer equipment and the other a motor-generator set to provide a low-voltage supply for control and lighting.

[28] In 1921-23, the Metropolitan Railway had ordered 20 electric locomotives for the locomotive-hauled services which they ran on the northern reaches of the line.

Driving motor cars at the outer ends of units were fitted with missile-proof windscreens, door opening controls, and high-intensity headlights.

[34] London Underground experimented with two all-over-advert trains, including a three-car C69 unit, which advertised Yellow Pages from 12 February 1998.

The vinyl adverts were removed in May 1999, after which it was moved to Acton in August, where repainting in corporate livery was completed in November.

[39] On 15 May 1969, two redundant driving motor cars of 1935 Stock were moved from Ruislip depot to Acton Works, for articulation trials.

The unit was subjected to testing for a year from August 1970, and after the trials, was retained as a works shunter, because the shoegear spanned over 64 feet (20 m), which meant that it could cross long gaps in the current rail at slow speeds.

The cars were numbered L14A and L14B, and it remained in use until early 1975, when the outer bogies were removed for other purposes, and the rest was broken up at the works.

The advantage of its length was realised, and a two-car shunting locomotive was constructed out of two redundant 1938 Stock driving motor cars in 1974.