Johnny,
Don't concern yourself regarding the juvenile remark, it isn't directed towards you.
But in the old days Brymon successfully operated 5 flights in each direction, per day, PLH/LON/PLH.
But ... because Brymon stretched the purse strings buying 3 x DHC7's they needed to sell the NQY HP7 (Dinosaur) thus PLH & NQY LHR services became combined and this happened because PLH had such a pathetically short landing strip the only airliners that could operate there were the 50 seater DHC7 or the 20 seater, fixed undercarriage, damn noisy, 150kt cruising speed, DHC6, one couldn't have an optimum sized aircraft on a route, perhaps 25, 30, 35 seat airliner, because no such STOL airliner existed!
I read a remark here recently that pax still complain (vomit) about the low level (bumpy) flights between PLH/NQY/PLH and memories returned, I did that journey one morning in a DHC7, a 15 (ish) minute flight that I can best describe as like being inside a tumble dryer, by the time I arrived in NQY my tie was at half mast and I was sweating profusely, it had been an extremely unpleasant experience that I didn't repeat.
Besides London, back then, Channel Islands and Ireland services were also successful along with summer operations to/from ISC.
But long ago a PLH runway became realigned and lengthened, limited other aircraft types, Do228, Do328 etc. could operate there but still the base airline insisted upon a 50 seater aircraft on a combined (NQY) and unpleasant/inconvenient schedule basis, I recall there was uproar from the Cornwall locals once they lost their direct services and became subjected to routing via PLH. at least then were transitting in the right direction of LHR, do you imagine the Plymouth locals were any happier being subjected to routing via NQY which was in the wrong direction from where they wanted to be?
I know hindsight can be a wonderful thing, some airline's ago, and due to particular circumstance(s), PLH & NQY services became combined, how many years ago was it that the PLH runway became realigned and extended, that's how many years the based airline(s) have had to uncombine these services however they have failed to do so, PLH airport has failed because the base airline(s) continued to operate an inappropriate size of aircraft!