altho' 50% of the population may live within 2 hours of MAN how many of those people even know there is an airport there, never mind the range of flights?
I'll bet more people travel from Leeds to LHR than MAN
partly it is due to poor trans pennine links but also the total lack of advertising as to what is available
also I'd expect that flights from Manchester and Birmingham to (say) the USA would be cheaper - but when I look the savings seem to be minimal over LHR