A Stuart triple expansion engine with Stuart centre flue boiler, set up for gas firing - the steam plant is completed by a hand pump for boiler feed, complete with tank. Beautifully made, the whole thing is mounted on an "engine room" floor comprising individually laid and grouted ceramic tiles. I found myself wishing the people who did our bathroom were as good...
Test steamed when new, since then it has only run on air - there's a clip made by the builder here.
Another model from the man responsible for the Galloway's non-dead centre, Westbury diagonal paddle, Corliss tandem compound and "ME" beam engines currently in stock.