45231 Sherwood Forester never officially carried a name whilst it was in service. It was built as 5231 - a member of the Black 5 Class - for the London, Midland and Scottish Railway in 1936, and mainly worked services between Leeds and North Wales.
The locomotive became 45231 after the creation of British Rail in 1948, and still carries this number today. It remained in service until the very last day of steam in August in 1968, and was preserved almost immediately. Having been named Sherwood Forester, the engine was an early acquisition of the Great Central Railway in Leicestershire, where it has been based since 1973.