Thanks Digin. St Erth would have been a good place. Didn't realise who owns Lands End; I seem to recall that BIH's plan was to close Lands End to light aircraft (?) which seemed a bit odd as St Mary's seems to work OK.
Earliest aviation memory was the BEA S-61N shuttling back and forth across PZ in mid-60s (that and being slightly scared by a loud and angry buzzing sound that turned out to be a Wasp!).
Finally got my ride out to St Mary's on the S-61N just before they shut the service down. Trip back on a perfect September evening was at low level around the coast past Lamorna and Mousehole - as much for the crew's benefit as the pax I suspect!