Yes we should move all those pesky DHC8s and ATR42s to Northolt.
Xeque you make a few good points but your certainty is undermined by your obvious unfamiliarity with the subject matter....
Last time I tried it, getting from T4 to either T1,2 or 3 took something like 30 minutes - bus or underground. How long does it take to get to any other terminal from T5?
On this point on T5, it shouldn't happen a lot, if you are on a codeshare you go through Flight Connections not the Heathrow Express or the Piccadilly Line.
I appreciate that a lot of you guys outside the capital quite sensibly use AMS / CDG / FRA. As a London resident however, I all too aware that even if LHR lost the entire connectivity to the rest of the UK it still needs a third runwy and a lot of TLC even just serving London ! Cameron will see sense when he takes up the real responsibility of office I hope.