The Class 55, also known as the Deltic, is a type of diesel-electric locomotive that was built in the United Kingdom during the 1960s. It is notable for its distinctive design and powerful performance, featuring two Napier Deltic engines. The Class 55 was primarily used for express passenger services on the East Coast Main Line. A total of 22 Class 55 locomotives were produced, and they became famous for their speed and reliability. They were retired from regular service in the early 1980s, but some have been preserved and are still operational today, showcasing the engineering achievements of their time.