Clas 55 'Deltic' locomotives outside the York Motive Power Depot, 1981.
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A row of Clas 55 Deltic diesel locomotives built by English Electric in 1961-1962. The fleet of 22 Deltics did the work of 55 A4 steam locomotives and cut an hour off the working timetable. Each powered by two Napier 'Deltic' engines, these locomotives were the most powerful diesels ever built when they were introduced. The Deltics continued in service until 1978, and were then transferred to York Depot where they were used until 1982.