clearly the foreign airports are in competition, i was referring to the other london airports. if one of them were expanded; could take traffic from heathrow and become a proper hub airport, then the airlines remaining at LHR would benefit from reduced delays. you're suggesting that london can only have one hub airport, plus some also-rans (LGW STN LTN), otherwise the whole thing wont work. i disagree. i think spreading the traffic out (planes and cars) would be a good thing. spreading the risk of disruption due to terrorism, major incidents at LHR or on the M25/M4 etc would be a very good thing.
BA and one world could still have its hub at LHR. Other airlines can go elsewhere. i don’t see the problem, i see benefits.
Northolt is a side issue - i have just always been surprised that we were prepared to build a runway on a small east end dock and yet northolt, with all its potential to serve the city of london, is virtually idle.