work. This vehicle was initially numbered L76, and took part in the Metropolitan Railway centenary celebrations, held on 23 May 1963, when it propelled a replica of the original inspection train of open wagons used by William Ewart Gladstone and other dignitaries. Metro-Cammell received the order for the next batch of thirteen locomotives, which were numbered L20 to L32. The first one was delivered on 8 December 1964 to Ruislip Depot. They were part of a programme to phase out the last remaining steam engines, but the Victoria line was also being built at this time, and some of the battery locos were fitted with automatic train operation (ATO) equipment, to enable them to work on that line. Traction control equipment was by GEC, with the batteries supplied by DP Battery Co Ltd. As with previous batches, parts of the locomotives were refurbished; in this case, the bogies, traction motors and compressors were supplied by Acton Works. Unlike earlier models, each vehicle was fitted with two compressors, allowing them to work singly. The last steam engines were withdrawn soon afterwards, and an order for five more battery locos was placed with Metro-Cammell in 1969. These worked on the Jubilee line construction, and were numbered L15 to L19. The construction of the Jubilee line and the Heathrow extension of the Piccadilly line required yet more works trains, and eleven more locomotives were ordered in 1972, with delivery in 1973. They were built at Doncaster Works by British Rail Engineering Limited. The motors were refurbished from redundant District line stock, but the bogies were new. Although based on the standard Z-type bogie used since the 1930s, they incorporated roller bearings, rather than white metal axleboxes and suspension bearings. Three of the locomotives were built to replace the three metadyne vehicles, but those were not actually withdrawn until 1977. A final batch of six locomotives was built by Metro-Cammell and delivered in 1985 and 1986. They incorporated all of the improvements made to the previous vehicles. For the first time, they were specified in metric units. New features included entry to the cabs through a central door, rather than a side door, strengthened windscreens with windscreen wipers, and the ability to charge the batteries while operating on electrified lines. One departure was the fitting of traction control equipment by Kiepe, which prevented them from working in multiple with any of the previous machines.