The British Railways' Class 55, also known as the Deltic, is a type of diesel-electric locomotive that was introduced in the early 1960s. Designed for high-speed passenger services, these locomotives were notable for their distinctive streamlined shape and powerful performance, capable of reaching speeds up to 100 mph. A total of 22 units were built, primarily serving on the East Coast Main Line between London and Edinburgh. The Class 55 locomotives were retired in the early 1980s, but they remain popular among railway enthusiasts and are celebrated for their engineering and historical significance.