In 1986, three trains were converted back for manual operation, and a 3-car unit worked the peak-only Epping to Ongar shuttle service, until that line closed on 30 September 1994.

One train still works as a track recording unit, while a second is in private ownership and has been used for railtours on the Underground.

Thus in 1935, four six-car trains were supplied by Metropolitan Cammell Carriage and Wagon Company, which were used as a test-bed for ideas which would be incorporated into the later 1938 stock,[1] while in 1986, three trains, each of four cars and built by different manufacturers, were ordered with subsequent larger orders in mind.

[2] The 1960 stock was part of a similar solution, and consisted of twelve motor cars, built by Cravens of Sheffield, incorporating a number of features which it was anticipated would form the basis for a major batch of vehicles to replace the pre-1938 stock then in use on the Central line.

In order to protect against wheel-spin, the controller automatically reset if one motor of a pair began to run faster than the other.

The 1960 stock avoided this problem by duplicating most of the connections in the automatic coupler, so that trains could be joined either way round.

[3] The 1960 Stock initially ran on the main Central line, before being cascaded to the Hainault Loop.

Conversion work included the fitting of fluorescent lighting, the addition of door indicator lights to the outside of the cars, and painting in silver paint, to match the unpainted aluminium of the motor cars.

Conversion work included the fitting of two compressors, as the pre-1938 trailers had been equipped with one each, but the process was costly, and only three sets were completed.

Since the trains were to be operated by one person, the door controls were moved from the rear end of the motor car into the cab.

The train control equipment was fitted beneath the centre seats, and consisted of a "black box", which interpreted signals received from the running rails.

The automatic control equipment was temporarily mounted in the passenger saloon, between the cab and the first set of doors, to enable engineers to monitor and adjust it as experience was gained.

[8] One unit was used to trial a system of fully automatic train control on the Woodford to Hainault branch in the early 1980s.

The original ATO equipment had reached the end of its life by 1986, and three trains were converted for manual one-person operation.