another thing,
The Senior Service always had a soft spot for the Scillies and used to visit several times a year with a landing craft and a helo to provide "logistical support" for the islanders. Their favourite activity being under-slinging cars that had exceeded their sell by date and depositing them offshore to provide "artificial reefs". An activity that has thankfully ceased now that the Scillies is a Marine Conservation Zone. The Navy's end of tour parties were legendary and seemed to leave the whole community shocked at how many empty bottles there were!
Incidentally, only a little while ago, end of July, I think, the lowest Spring Tides for a long time made it possible to walk, well paddle actually, between St. Mary's, Tresco and St. Martins
I was at St. Mary's in 1983/4 a little before you and sadly my first week coincided with the crash of G-BCEB. A great loss to a small community.
OTB