The class was built for working passenger services on the West Coast Main Line (WCML) north of , to , , Carlisle, and Perth, occasionally reaching as far north as Aberdeen. Services south of Crewe would generally be worked by an electric locomotive, with the Class 50s taking over for the journeys that continued north. Initially trains were hauled by a single locomotive, but from May 1970 they were paired on 8 out of 34 locomotive diagrams covering Anglo-Scottish services north of Crewe, allowing greatly accelerated timings to be applied (including a six-hour schedule for the "Royal Scot" London Euston-Glasgow Central and v.v. service). Once the electric service was introduced as far as Preston in 1973, this double-heading by Class 50s transferred there, although poor availability often resulted in single-heading with consequent delays. The ability to operate using multiple working had been part of the locomotive's initial design brief, but only two of the class had the facility from new, but with the introduction of the regular double headed duties, this facility was fitted to the whole class.