Sir Nigel Gresley was a prominent British locomotive engineer known for his innovative designs in the early 20th century. He served as the chief mechanical engineer for the London and North Eastern Railway (LNER) from 1923 until his death in 1941. Gresley is best known for creating the famous A4 Pacific locomotives, including the iconic Mallard, which holds the world speed record for steam locomotives. Gresley's work significantly advanced steam locomotive technology, emphasizing efficiency and speed. His designs, characterized by streamlined shapes and powerful engines, revolutionized train travel in Britain. Today, Gresley is celebrated for his contributions to railway engineering and remains a key figure in the history of British railways.