Cornishsimon,
Remarkable job being done on growing the traffic ex Newquay, great to see the airport progressing. Cornwall is a great part of the Country so continued success.
The LHR piece may well work but it is the common theme, it is not so much that it would work but rather that other routes are far more lucrative. The charges for flying to /from LHR make it prohibitive for short point to point flying ( large part of the problem that Bmi had). so LHR would be largely transfer pax, And adding lhr woyld impact LGW, so may not be a great addition in they long run.
And while not to down NQY, LBA, if it had the right schedule it may well do a lot better, but again the commercial argument comes into play there too. I'd say that LBA is marginal at best, probably in excess of 75% of pax are transfer...