Looks as if the Iron Horse on the mower itself has its carburetor and reed valve missing, so it's a posed pic I think. There may be some kind of subtle steering system in play there, but I haven't figured out how it works. By the look of the huge tyres on his powerseat, either he was rather a big lad, or he goes up some steep hills with that rig. I think there is some serious ingenuity involved in the design, Deejay, not a typical tenant job. Maybe a prototype for a project that never happened.
