Fred, thanks, know it was Mitchell that invented the Spitfire, and couldn't remember the name of the chap that invented the jet engine. Know it was definitely a shed, albeit a very big one, as in one of his tests he couldn't get the thing to switch off, and before he could cut the fuel supply it went bang and set fire to the shed.
Think I need a shed, without one the only thing I could come up with is a radio-controlled rat in order to scare ladies (and some men) everywhere. Of course, it would be marketed as a cat toy - I'm sure no-one would buy it in order to scare their mum! Or Calorie-free chocolate, but then I'm sure that there are several genii with a few million working on that one as we speak - the inventor of that would make an absolute fortune.
Several people in the area have sheds, very posh ones, with hot-tubs in them. What a waste!