FF, was the Brit version sometime back in the '80s? I don't recall reading about it during the '90s.
Yes I've got old routesheets for it (I know!) from 1984 and 1985. It was a 300 and 600 on consecutive weekends, with a midweek 400 and the 200 slipped in somewhere, I don't think it was actually back to back with the 300 so it was probably on the Monday, so probably the August bank holiday Monday, I know it was late summer. Obviously a cunning ruse to drum up trade for Salisbury YH. I only rode the 400 and 600.
Sheila reminds me there was also an SR week - indeed, a PBP qualifying week - held in the north of Scotland, also in the early 80s. Based just north of Inverness.