Several people identified this one - thanks to everybody who emailed. H.Clarkson design using their castings we believe - I should have looked at the Clarkson catalogue that's on my bookshelf.
A 5 inch gauge Prussian P8 - it's from the large collection of engines that John and I collected from France last week, the late owner's huge old country house about to be demolished to make way for apartments. Not sure whose castings or drawings were used in the construction - it's nicely built with fine finish on the valve gear and motionwork, and nice details like split bronze axleboxes and cottered big ends. Boiler is stamped April 1980, P8/34 with a working pressure of 90psi - and that's about the sum total of what we know of the engine. If anyone knows any more about it, we'd be pleased to hear from you.
Largely complete, the chassis is seized from having stood for many years in the owner's house - wouldn't expect it needing anything more than gently freeing off with some light oil. Brake hangers are fitted, but no shoes or linkage. Boiler is silver soldered, beautifully made and fitted with a four element superheater. Gunmetal cylinders have piston valves actuated by Walschaert's gear, there's a finely made screw reverser in the cab with locking bar and two start square-cut thread. Connecting and coupling rods have split and cottered big ends.
An interesting project, something not seen too often on these shores.
Locomotive 42 inches
Tender 27 inches