Bakerloo line
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.