King James I was a GWR 6000 class 4-6-0 tender engine who worked alongside Duck in the days when he worked at Paddington. King James I was built in 1928, withdrawn in 1962, and was scrapped at Swindon Works in 1964. Duck once compared him to James. He is named after King James I of England.
King James I was painted in the Great Western Railway's, and later British Railways, Brunswick green livery with orange lining.