During the time of British Rail, the Class 37s found use on both passenger and freight workings, being one of the mainstays of the BR fleet. While freight use was widespread, passenger work was predominantly in the Eastern Region with use on London - Norwich and Cambridge/King's Lynn services, the latter through to the 1980s and in West Wales on services west of Swansea to Fishguard Harbour, Milford Haven and Pembroke Dock. Darnall's (later Tinsley's) 37s were used on various passenger services in the Sheffield area, notably the Pullman service to London King's Cross. Hull Dairycoates' 37s were used on local stopping services as well as on King's Cross portions down to Doncaster.