This is the only model I know of made by Midland Models. The engine unit was also supplied to SEL who sold it under their name as the SEL 1560 with minor modifications to the cylinder and flywheel (it might be an earlier or later version). In turn, SEL sold their surplus stock to Mamod for use in their ME3.
The horizontal boiler is 5.25" long x 2" diameter and has a pair of Babcock style water tubes underneath. It is fired by a rather dangerous looking 4 wick meths burner; the meths tank is mounted above the level of the wick holders! The boiler is fitted with a filler plug, a safety valve and a steam take-off. There is no water level indication. Steam is fed via a displacement lubricator to the back of the engine port face. The single acting oscillating cylinder is 7/16" bore x 1/2" stroke.
As acquired, the boiler was fitted with a bolt for the filler plug (not original and wrong thread anyway). The safety valve was blocked and siezed solid, apparently glued, possibly deliberately. I bought a new safety valve and modified the old one to replace the filler plug. I don't trust the burner, which is also blocked (also deliberately?) so I'm firing it with a Mamod burner.