I don't know what this is, if you think you do, let me know.
It came from a collection recently arrived which included the Class 15 Bo-Bo and several steam locomotives. This was the last engine that the gentleman worked on, he had got on well with a rolling chassis and ordered a boiler from Western Steam. There were a huge pile of drawings that came with the workshop, including some much pencilled on Tilbury tank plans - these match up with the boiler dimensions (18 inches overall length, barrel 4 1/4 inch diameter), but the chassis is patently not that engine.
Whatever it is, work to date is nicely done, the chassis rolls freely, wheel quartering and rod lengths are all ok, cylinders are machined and erected complete with valve chests. Eccentric sheaves are machined and fitted, straps and expansion links are machined - there are almost enough parts to get an air-running chassis.