No, I meant Manchester. Ok, yes, BHX has a fairly good spread of flag carriers and serves the Midlands quite well, but it's really too close to London to be able to sustain a market for longer routes. Manchester is far enough away to be able to sustain a market in the North and some of the Midlands, due to existing volume and excellent (and improving) surface access. The Northern market is big enough for one such airport, but only one. If that market gets fragmented - as it has threatened to do in the crazy Noughties - the North will end up with a scattering of marginal regional airports, all struggling to sustain a meaningful route network. In withdrawing from Liverpool KLM have realised that serving airports 30 miles apart, except major hubs, is saturation rather than comprehensive coverage.
A strong MAN will provide a mini-hub, or at least a spoke on many networks, to compliment the London airports. It won't try to take passengers from the South, only those Northerners who might otherwise fly from London. That is why I call MAN a national airport - it serves perhaps half of the UK population across several regions and forms part of a national airport infrastructure. The 1978 White Paper got it nearly right - except for Prestwick. The 2003 'everyone grows' version needs binning - it was dreamland.