The trains, which were allocated to Croxley Green depot, were withdrawn from operation in May 1985. The trains on the east–west orbital service, from Broad Street to Richmond, were replaced with Class 416 units from the Southern Region, from the first day of the service being diverted and extended from Broad Street around eastern London to North Woolwich station. Services between London Euston/Broad Street and Watford and on the Croxley Green branch were subsequently replaced by sliding door Class 313 units. Service reduction The services they were used on were subject to considerable contraction during their lifetime. The 57 units initially replaced the 77 LNWR "Oerlikon" 3-car sets on these lines, and the 25 additional sets built by the LMS in 1927 (giving over 100 3-car sets on these lines) were withdrawn in the early 1960s without replacement. After this numbers of the Class 501 were subject to early withdrawal in the 1960s-70s (45 of the 57 units remained in traffic by 1976), and the final stage was reached where they were replaced by a small number of class 313 sets which were spare from the 1970s GN electrification. The Richmond lines were initially covered by ex-SR sets as stated above, but ultimately all the 501s territory was covered by 313s which had become spare. Furthermore, the London Underground Bakerloo line, which initially shared the system from Queens Park to Watford, was very substantially cut back and ultimately withdrawn north of Harrow & Wealdstone. The decline in traffic on the 501s' territory is unparalleled by any other electrified service in London. The substantial peak services operated by the units from London's Broad Street terminus, to Richmond and Watford, were completely withdrawn during their lifetime. Numbering British Railways numbers were: Motor Open Brake Second, M61133—M61189 Trailer Open Second, M70133—M70189 Driving Trailer Open Brake Second, M75133—M75189 Further use Ten Class 501 DMBS carriages were converted to Class 97/7 battery locomotives. Two carriages, DTS 75186 and TS 70170, went on to work at MOD Marchwood. Three two-car units were converted to Class 936 sandite units, and saw use until the early 2000s. Two 3-car units (xx162 & xx165) were transferred to the SR as Departmental Test Units 051 & 052 in 1969 but did not last long. Formations: 051: M61162 - DB975027; M70162 - DB975028; M75162 - DB975029. 052: M61165 - DB975030; M70165 - DB975031; M75165 - DB975032. 052 was withdrawn by 1970