In 1970 the one way fare on Westward Airways BN2A Islander was £18 from LHR to ISC via PLH and NQY, not sure about the return fare but PLH was slightly less if I recall. LGW/LHR was £4 one way and £5 for a day return, wrote all the tickets out by hand, still have some blank ones so thought about turning up at Lands End with an ISC one made out to see what the reaction is! Publicity stunt perhaps!!.
There was virtually no advertising, no interline agreements and as I recall a lot of staff travelled on the flights, possibly why there were few passengers.. By 1971 it was all over until Brymon came along.
Years later,when BA pulled out of the prop market it is rumoured NQY was the most profitable route they did. The fare then was £250 so it doesn't have to be cheap...