But LCY is useless for international, particularly long haul, connections, LGW or LTN are the airport(s) that offer the best all-round solution, PDQ trains in to London or National Express to/from LHR.
But FlyBE's equipment is too large for the route, and it is likely that it shall always be too large for the route, and I would suggest that it inappropriate to offer a subsidy to an operator that is never likely to break in to profit on a route either because the route and/or the equipment are wrong.
And as for Ryanair, if the quoted 20 seat subsidy is correct, well that's going to be hilarious, particularly during the winters, I bet the council tax payers of Cornwall are really welcoming the though of their council tax subjecting them to gawdy cabins, stale sandwiches and warm beer!