Well with Penzance and Plymouth closed, and with Lands End being a Skybus monopoly that only, realistically, leaves Newquay for ISC operations with a BN2 or DHC6 operating such a route.
EXT might also be a consideration but with little if any refueling facility at ISC EXT becomes a restricted load long haul operation whilst Skybus, from Lands End, will have the shortest route and fuel burn to put out of business any competitor from further afield.