Central line services - they were mixed with the Northern and Bakerloo line fleets. Throughout the 1950s and 1960s, the Northern line was worked exclusively by 1938/1949 Stock trains. They were starting to show their age by the late 1960s; the first withdrawals from the Northern line took place in the early 1970s with the introduction of the 1972 Stock trains. In the mid-1970s, the 1972 Stock (Mark II) cars began to be used on the Bakerloo line in addition to 1938 Stock. The 1972 Stock cars were intended for eventual use on the Jubilee line (which opened in 1979), thereafter the remaining section of the Bakerloo line continued to be served exclusively by 1938 Stock cars until the 1980s. The Bakerloo line trains received an "Extra Heavy Overhaul" (EHO) to keep them in service long after their intended withdrawal date. The Bakerloo line was thus the last line to be operated solely by 1938 Stock trains. The Piccadilly line's few 1938 Stock trains operated alongside 1959 Stock for much of their lives. They were replaced by London Underground 1973 Stock, with the 1959 Stock being transferred to the Northern line, replacing other 1938 Stock trains. During the 1970s, the short East London Line was worked by 1938 Stock trains, replacing trains of Q Stock. Single 1938 Stock trailer carriages were also inserted into 1960 Stock trains in the mid-1980s; these were used on the Woodford–Hainault and Epping–Ongar sections of the Central line. In addition, unit 10177 (latterly shipped to Alderney) worked the Epping-Ongar shuttle between November 1957 and June 1960. With the 1959 Stock approaching life-expiry, five ex-Bakerloo line trains of 1938 Stock were given a further overhaul in the mid-1980s. These were then used on the Northern line for a further two years, the last day of passenger service was on 19 May 1988. They were then sold for further use on the Isle of Wight (see below). Nine-car trains As part of the New Works Programme of 1935–1940, there were plans to operate nine-car trains of 1938 stock on the Northern line. These cars were originally numbered differently from the other cars, the first digit '1' being replaced by a '9'. The formation for a nine-car train would have been DM + NDM + SNDM + T + NDM + T + SNDM + NDM + DM. With the scaling back of the planned extensions for the