No sooner has one 4 1/2 inch Simplicity gone out than another appears. This one has been on display in a living room for the last ten years (it was a very big living room), after a hydraulic test on the boiler Ashley had a happy day cleaning and oiling round before giving it a run in the afternoon. It goes particularly well, very quiet with the motionwork showing no signs of any serious use - there's a video of the engine running here.

Silver-soldered copper boiler, feed by mechanical pump and injector with auxiliary hand pump on manstand. 
Twin safety valves, water gauge with protector and blowdown. Boiler blowdown valve beneath belly tanks. Single cylinder with slide valve actuated by Stephenson's valve gear with pole reverser in cab. Single road speed engaged by pin on the right hand hornplate, as per the prototype.

Length 55 inches
Height 38 inches to top of chimney
Width 24 inches across rear rolls
Weight 500 pounds

(and before anybody asks why this Simplicity weighs 500 pounds when the one I sold two weeks ago was listed as 400 pounds, I've just taken delivery of a very smart new set of Salter weigh beams which will weigh up to 2 1/2 tons in one pound increments, so weights listed from now on are "definitive"!)