6201 'Princess Margaret Rose' entered service in 1935, named after the then five-year-old daughter of Albert, Duke of York (later King George VI), Princess Margaret Rose, the younger sister of Queen Elizabeth II. The locomotive was used to haul LMS passenger trains from London to the north and northwest of England and to Scotland.

After nationalisation in 1948, British Railways renumbered it 46203 before it was withdrawn from service in 1962. It was one of two Princesses to be preserved and was restored to mainline specification in 1990 before later being placed on static display in the West Shed at Swanwick Junction.