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 King James I was built in 1928, withdrawn in 1962, and was scrapped at Swindon Works in 1964.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. Like the other engines in his class he is named after a English King, he being named after King James I of England.
King James I was painted in the Great Western Railway's, and later British Railways, Brunswick green with orange lining.