Appears it is a Ahaigh York , the current owner didn't keep care of it very well , it has noticeably deteriorated.
It is too bad the engine looks worse. I hope the new owner spruces it up.
As for Darlington, I suspect it's Darlington in England.
Nick, you missed out on a tremendous deal even if it was worth only a $100 as it is such a fine piece. In 2008, I think I would have offered him $500 on the spot for it. I never see such things at flea market area at the tractor shows. Admittedly I only skim them as I'd rather look at the machinery. (There is a lot at the market area that wouldn't interest many.)