London Underground C69 and C77 Stock

C Stock is the name given to the trains currently running on London Underground's Circle and Hammersmith & City lines as well as on the District Line between Edgware Road and Wimbledon. They are maintained at Hammersmith Depot.

Construction
They were built in Birmingham by Metro-Cammell and delivered in two batches, known as C69 (1969–70) (35 trains) and C77 (1978) (11 trains). The C69 Stock was purchased to allow the transfer of CO/CP Stock from the Circle Line and Hammersmith & City Line to the District Line (in turn allowing the replacement of the District's Q Stock, the oldest of which dated back to 1923). The first C Stock train entered service in 1969.

The C77 Stock was purchased for the District Line's to  service, which is unable to use the District Line's D Stock because of short platforms between  and Edgware Road. The introduction of the C77 Stock allowed the withdrawal of some of the CO/CP Stock. One additional car was added to the C77 order to replace C69 car 5585, which was damaged in the West Ham terrorist bomb incident in March 1976. The driver was killed. Unit 5585-6585 thus became a hybrid C69/C77 unit and was selected for a trial refurbishment in 1989, which was carried out at BREL, Derby.

Unit cars 6505 and 6713 were the vehicles within which the 7 July bombings occurred and both were subsequently scrapped above the solebar. The remnants were utilised in the building of two new vehicles numbered 6606 (the second vehicle of this number) and 6734; these vehicles being known as C08 stock. The new vehicles were paired with 5505 and 5713 but both renumbered as 5606 and 5734 to match their partners. 5548+6548 were rebuilt in part following their involvement in the events of 7 July 2005. The C08 stock that was rebuilt, as after the retirement will be preserved in London Transport Museum (Acton Works).

Design
There are four sets of double doors per car side. When originally delivered, the cars were divided by partitions adjacent to each set of doors, with 2 facing pairs of transverse seats on each side of the aisle, giving limited standing room. The partition wall contained a large back lit advertising space above the aisle opening. When the stock was refurbished in 1990-94 all these features were removed.

Each six car train consists of 3 units of 2 cars each, all trains having three cabs. They are all painted in the London Underground corporate livery.

Numbering
C69 Stock DMs were numbered 5501-5606 and renumbered 5606(2) plus trailers 6501-6606. The original 5606 and 6606 were scrapped in the 1990s. The C77s are 5585(2), 5701-5733, 6701-6733 and renumbered 5734. The C08s are 6606(2) and 6734.

Planned withdrawal
The C Stock will be replaced between 2012 and 2014 by the new London Underground S Stock trains. . Sets 5595+6595 and 5596+6596(?) were cannibalised in 2011 as a trial program, and this will result in a planned withdrawal until 2014. The first withdrawal will take place in April 2012.