The Wilesco "Old Smoky" steam roller goes back several decades and hasn't changed much in that time. I have been advised that this example is about 1977-8, based mainly on the rather mutilated label on the rear of the bunker, but with a few other clues like the handles on the burner tray, throttle and whistle. The model is now called D365 but I think was probably known as the D36 at the time this one was made, or just as "Old Smoky". I'm not sure when the changes came in.
The Wilesco roller has many enhancements compared with, say, the Mamod equivalent; some cosmetic and some functional. Things like the double acting "piston" valved cylinder and geared drive give the engine a much more realistic running speed (but still too fast for scale accuracy) The steering is through a chain, similar to the real thing. Pressed steel parts like the front fork and smokebox look a bit more realistic than the Mamod, but are more prone to damage because of the thinner material. The wheel spokes are an exception in that the Mamod die-cast spokes look much better.
The burner is a standard Wilesco Esbit fueled type fitted under the rear end of the boiler. The boiler is approx 165mm long x 45mm diameter. It's not easy to measure because it's enclosed in an outer covering. At the rear end is a typical Wilesco round water level sight glass; somewhat obscured by the dummy bunker, which is not removable. Also fitted are safety valve, throttle and whistle, all pretty standard Wilesco style.
The steam pipe comes out of the top of the throttle, round a loop to the under side of the valve chest. The valve is the usual Wilesco type, sometimes called a "Piston" valve because it's round but is not a true piston valve, closer to a slide valve but round in shape. A drip feed oiler is fitted on the top of the chest. The valve controls steam into a double acting cylinder, and is itself controlled by a slip eccentric on the crank shaft.
The piston is 13mm diameter (assuming it's the same as the D16, which is a good bet). Stroke is measurable at 16mm. The main piston rod is connected to the crank via a con rod with no cross slide. The crank and slip eccentric are together at one end of the crank shaft. At the other end is a 78mm diameter mazac flywheel. Exhaust steam is fed from the valve chest into the smoke box to be exhausted through the chimney.
Drive from the crank shaft to one rear wheel is via a two stage gear train, unfortunately using thin pressed steel gears which sound very "tinny" while running. A lever shifts the final gear in and out of mesh to allow the engine to idle freely. The wheel spokes are disappointingly tinny in appearance. This applies, also, to the front rolls but is less obvious there.
The front rolls are steered by chains wound round a spiral shaft which is turned by a contrate gear and a spur gear attached to the steering wheel. The rear part of the engine is covered by a half length canopy.
As acquired, the machine as a whole was in generally good condition but was in need of attention in a few places. The canopy mounting pillars were loose on one side due to missing nuts (now fixed). The plastic whistle handle was melted. (Not surprising as it's mounted on top of the firebox!) I don't like the modern Wilesco handles, which would be out of character anyway, so I've temporarily replaced the handle with a nut and bolt. The throttle lever is loose but there isn't much I can do about that short of replacing the whole throttle. It's still functional but it's difficult to set a desired speed. The gears driving the steering were badly damaged, (by the looks of it, caused by an attempted repair with an arc welder!) I have replaced those. The paintwork is mostly good with no obvious rust.