The Class 31/1 became the standard locomotive and with several differences from the first 20locomotives that were designated 31/0.
They all had steam heating boilers fitted and had a route availability of 5, which meant they could go anywhere on the British Rail network and could commonly be found on secondary and relief passenger traffic as well as parcel and freight trains. Whilst mainly used in East Anglia being allocated to Stratford and March Depots, they were also common throughout the Eastern Region of British Rail with depots at Finsbury Park, Thornaby, Immingham and Tinsley being allocated a significant number of locomotives. Bristol Bath Road and Old Oak Common on the Western Region also seen allocations of the class and these worked trains as far as Barnstaple and Paignton and other resorts on the Cornish Riviera. In the early 1980's, the Midland Region depots of Healey Mills and Bescot seen several Class 31/1's allocated as a replacement for the ageing Class 25 loco's.
These were in the TOPS number range 31101 - 31327 and were introduced between 1958 and 1962