That's interesting stuff TheLocalYokel. The only problem with that is you could easily consider Nottingham (825,600), Leicester (772,400) and Coventry (651,000) as part of the Birmingham catchment area totalling 2,249,000 plus Birmingham itself come to 4,606,100.
LUZs aren't aimed at airport catchment sizes. They are a device to more accurately assess populations of an urban area/conurbation beyond the strict municipal definitions of city populations.
As you say, some of the LUZs will overlap when it comes to airport catchment areas.
one of them is in general decline (BHX),one no longer has flights (CVT) and only EMA is showing growth.
EMA has lost around 27% of its passenger numbers since 2008 when it handled 5.62 million passengers in the year. It's now down to fewer than 4.10 mppa (January 2011) and shows no sign of improving. In November its passenger numbers declined by 18.9% on the previous November and in December it saw a decrease of 24%. In January it was down by 12% even though January 2010 was severely weather affected.
BHX, like most airports, has declined since its best year (in its case 2008 when it handled 9.58 mppa) but only six UK top 20 airports have fared better since the recession bit. Its passenger figures are down by 10.6% since his best year.
It is true that BHX is having some trouble in attracting new routes/operators given its size but I can't in any way see it is performing worse than EMA: the reverse in fact.
I'm not a poster who has a football club-like allegiance to any airport. My local airport is BRS and I use it most of the time because it's convenient. LHR, BHX, CWL, EXT and even SOU are all in range and I will use them if they are better options though I don't like giant airports, hence my aversion to LHR.
My long haul alternatives to LHR are BHX (limited) or via AMS/CDG/BRU/DUB from BRS. This is the reason I'd like to see BHX find some more lh routes. However, I recognise its geographical situation between the southeast mega hub and the northwest major hub makes life potentially difficult in this regard.
MAN is certainly starting to do very well again but it has to be remembered that it lost 20% of its passenger numbers since its high point in 2006 when 22.12 mppa were handled so it has some work to do to get back to that level.