The London Underground 1973 Stock is a type of rolling stock used on the Piccadilly line of the London Underground. It was introduced into service in 1975 with the extension of the line to Hatton Cross in 1975, followed by a further extension to Heathrow Central in 1977.

In the early 1970s London Transport placed an order for a new fleet of trains to replace the 1959 stock, the 1938 stock and 1962 stock vehicles  which previously operated on the Piccadilly line.

Built between 1972 and 1975 by Metro Cammell in Birmingham, the first unit entered service on 19 July 1975 and the last was introduced by 1977. The trains featured longer cars and larger door space than the previous ones, being designed for airport travellers with luggage.

Finding tube stock is not easy so I've gone to a few bring and buy model train shows lately and purchase  some old Mark 1 British Railways’ lines coaches

Cutting the top window off and lowering the roof by 8mm.

The next stage will be to add engines and change the coupling to bring the cars closer

so far so good