Only just noticed this post, But there is a 150 Landmaster for sale on that auction site, It has the original engine by the look of it, it is a J.A.P. and seems to be a two stroke, the advert says that it is 4 HP I dont know what 2 stroke japs were made in that HP . At the time that machine was sold J.A.Prestwich had been sold to Villiers who carried on making them for a while, I have a 150 myself, but fitted with a later B&S engine.