A few more points.
Firstly, for all those advocating Birmingham or Manchester as an alternative hub (generally the inhabitants of those two areas), past history has shown that the demand just isn't there. You may feel it suiits you, but there are key differences.
Firstly the premium class high-margin demand from those points just isn't there, in comparison to London. Any mainstream operator will tell you that of the premium demand from the UK, the vast majority is from London. People just don't book F or J from Manchester or Glasgow in anything like the proportions that they do from London, Paris or Frankfurt, which is a sure way of demonstrating they are very secondary business destinations. The relative demand at different places is just a fact of life - even in London, LCY and LHR are good for premium traffic, LGW and STN (especially) have shown that, even where it is provided, there just isn't the demand for it.
Secondly we hear all the stuff about the population of the UK that is closer to those points. Well, not only are they not travelling nearly as much (or in premium - see above), but for INBOUND passengers from overseas coming to the UK, the vast majority (I would guess 80% plus) are headed for London, and inbound pax are probably half or more the total load at Heathrow. You notice this with, say, American's flights from Chicago, 4 daily to London and one to Manchester. To London, US passengers predominate, to Manchester they are very much the minority, it's just Brits from the north.