Always been one of my favorites in the 80's on Fairport, although it was on a Swarbrick Nicol album originally as has already been mentioned. I always suspected it might be an amalgamation of known incidents from throughout England put together within the song, but I have no proof of that, its just my thought. You could try over on the talkawhile forum. Both Simon Nicol and recently, Swarb himself post on there, and try to set the record straight. ALso a lot of deeply knowledgeable people of every aspect of the Fairport history who might know for sure.