These were built in UK by John Allen of Oxford from about 1938 for about 40 years. They were often used by smallholders to cut grass for hay and by councils to clear undergrowth, nettles brambles etc, in the years before brushcutters. A range of accessories, pumps generators even sheep shearing kit were sold I believe.
Early ones had a 147 cc two stroke Villiers ( 11 c I think) with a hit/miss governor on the points cam to limit revs to 2000 so they sound like they are four stroking. Truly built to last many are still working . The tyres shown are correct . Very dangerous to use or be near. The self propelled drive is by a sort of dog clutch that tends not to release when under load- worse than that the revs drop, the governor leaves points working and the engine really works hard digging the wheels in and cutting through almost anything .
My friend who worked on them in the sixties and seventies said dogs with a foot missing were often to be seen on smallholdings that had them . .
Some clips on Youtube show brave souls using them
