[2] The trailers and French motor cars formed the inaugural train on the Hampstead Line extension from Golders Green to Hendon when it opened on 19 November 1923.

[3] The builders were given a partial specification, which ensured that each car would have 48 seats and two sets of air-operated double doors on each side, providing an opening which was 4 feet 6 inches (1.372 m) wide.

Beyond these basic guidelines, each builder was allowed to build a trailer car to its own design, although externally, they looked very similar.

[4] The earliest Standard Stock was built for use on the Hampstead tube, which was extended from Golders Green to Edgware and from Clapham Common to Morden in 1923, as well as incorporating the City and South London Railway, which had been rebuilt with larger tunnels.

[5] The City and South London Railway had been built with tunnels which were only 10 feet 6 inches (3.20 m) in diameter, and had used small electric locomotives to haul trailer cars, until it closed for rebuilding in 1923.

[5] In a departure from previous practice, where all traction control equipment had been supplied by British Thomson-Houston (BTH), most of the batch were fitted with equipment by Metropolitan-Vickers, which consisted of electro-magnetic contactors arranged to manage the acceleration of the train automatically, with switching from series to parallel connection of the motors handled by bridging them rather than open-circuiting them.

The inter-operability of cars from several manufacturers with three types of traction control was the reason that they were called Standard Stock.

[11] During this period, many of the Gate Stock cars on the Central line had been converted to air-door operation by the Union Construction Co., which was based at Feltham.

The lightweight construction caused problems in later years, when the seat risers and body bolsters developed fractures.

The position of the guard's door control panel was altered, although this was not found to be satisfactory, and was dropped from subsequent builds.

[13] Because of the Piccadilly extensions, which were above ground, heaters were fitted, and the use of British materials in its construction was used for publicity purposes, at a time when there was an industrial depression.

62 production cars were ordered from Metropolitan-Cammell, which was formed from the Metropolitan Carriage Wagon and Finance Co. and Cammell Laird at this time, for delivery to the Bakerloo line.

They replaced the Watford Joint Stock, which although relatively new, needed a larger crew and had to stop for longer at stations, because of its swing doors.

Previous builds of Standard Stock were gradually altered to include the extra wires, a process which was largely completed by 1936.

[16] The final build of Standard Stock was a small batch of 26 motor cars ordered from Metropolitan-Cammell in 1934, after the formation of the London Passenger Transport Board in the previous year.

[18] By the time the final cars had been delivered, the standard stock was operating on the Northern, Piccadilly and Bakerloo lines.

Additionally, it had a non-standard arrangement of the third and fourth rails which supplied power to the cars, and these were modified to the same configuration as on the Northern line during the refurbishment.

Others were stored on sidings at Edgware, Golders Green, Highgate, Morden, Neasden, and Stanmore, as well as in depots where there was spare capacity.

Some trains were used for "Tube Refreshment Specials", supplying food and drink to people sheltering from air raids on the underground platforms.

[24] The effects of six or more years of open-air storage on the Standard Stock was severe, and a programme of heavy refurbishment began, which included replacement of warped window frames, renewal of corroded equipment as necessary, and in many cases, complete rewiring.

This arrangement was not ideal at busy times, since there was a section in the middle of the train where there were no passenger doors for almost 50 feet (15 m), caused by the switch compartments behind the driving cabs.

This enabled the first large-scale withdrawals and scrapping of Standard Stock, although some of the better cars were transferred to the Central line to complete the 8-car trains.

[29] London Transport intended to use the prototype 1960 Stock to develop new trains to replace the Standard Stock on the Central line: however, the condition of the 30–40 year-old Central line fleet were deteriorating under an intense service pattern, exacerbated by growing demand from the expansion of electric trains in the Eastern Region of British Railways.

[39] Overhaul of the electrical and braking systems was done at Acton Works, which involved transferring the cars from Micheldever back to London Transport.

[40] They were loaded onto a road vehicle at Fratton belonging to the haulage company Pickfords, and crossed to the island on the Portsmouth to Fishbourne ferry.

Apart from those cut up following accidents at Ryde depot, and other early withdrawals, most of these units were withdrawn between 1988 and 1991,[42] when they were replaced by London Underground 1938 Stock.

They worked under their own power between Fratton and Wimbledon, and were displayed at an open day at Morden Depot, celebrating 100 years of the Northern line.

This was a government initiative in the aftermath of the First World War to fund schemes which would create employment, particularly in the construction, steel and manufacturing industries.

The Underground benefited from £5 million of investment from this source, which in addition to funding extensions to the Northern line, financed the construction of over 1,100 Standard Stock cars between 1922 and 1930.

It underwent restoration in 2014 and is on static display at Epping Tube Station, repainted from London Underground red into engineer's yellow.