The British Rail 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 twin-engine design, which allowed them to achieve impressive speeds. A total of 22 units were built, primarily for use on the East Coast Main Line. The Class 55 locomotives were powered by two Napier Deltic engines, which contributed to their unique sound and performance. They were primarily used by British Railways until their retirement in the late 1980s. Today, several units are preserved and can be seen at heritage railways across the UK.