It is a LMS Stanier Class 5 4-6-0 locomotive, originally numbered 5212 by the LMS, it had 40000 added to its number under British Railways after nationalisation in 1948. 45212 was one of the last locomotives to be withdrawn from service, surviving until 1968, the last year of steam on British Railways.
45212 was purchased directly from British Railways service for preservation so never had to be restored from scrapyard condition unlike other preserved locomotives which ended up being sent to Barry Island. The majority of its class including 45212 were purchased directly from BR service for preservation with only six being purchased from Barry Island and then required restoration to run again. Before being overhauled at Ian Riley's workshop in Bury it spent most of its previous boiler ticket operating at the North Yorkshire Moors Railway, but was not able to run trains into Whitby or Battersby as it was not mainline certified.
