A really nicely made example of Charles Kennion's "Chub" design, a beginner's 0-4-0 tank engine, little sister to his 0-6-0 "Butch".
Silver soldered copper boiler, working pressure 80psi, feed by axle pump and injector. Slide valves actuated by Walschaert's gear with pole reverser in cab. Mechanical lubricator on nearside running board driven by a very elegant linkage, well though out and nicely executed.
Fit and finish of the motion work is good, the engine show very little wear either to wheels or valve gear. It runs well with regular, well-defined exhaust beats (and, with an over-enthusiastic hand on the regulator the motion disappears in a blur of rods. Apparently). The axle pump is to the standard Kennion design with a slot cut in a sold gunmetal body, allowing the ram to be supported at both ends - it works well. The injector is small, home made and with a clack mounted close-coupled to the body - it works, but a small commercial injector would require a less delicate touch on the water and steam valves (which is a polite way of saying it works but you have to watch it, whereas I like injectors where you turn on the water, bang on the steam and assume they're working unless you hear otherwise).
Driving wheels 4 inch diameter