This locomotive was supplied new to NCB Scottish Division, Area 7, at the Michael Colliery, as No.20, renumbered at the Colliery as No.21. After the disaster which closed the Michael in September 1967 it moved to Comrie Colliery, where it was renumbered '5'.
This is a standard World War Two austerity design of locomotive.
The boiler smokebox is fitted with a Giesl ejector to improve steaming and to allow poor quality coal to be used.