What routes do you have in mind which would replace the loss of LHR?
Not sure of your point. Are you saying NCL have been threatened with the loss of LHR and therefore feel obliged to support its expansion?
I wasn't suggesting that NCL accept the loss of LHR connections but surely it's important for Northern airports to gain as many direct services as are viable rather than have passengers forced to change as Dobbo said. Airlines don't have an unlimited number of aircraft, and expansion of LHR is bound to result in some airlines increasing frequencies from there on some routes to use the extra slots available. This, in my view, could be to the detriment of existing direct services to some UK regional airports.
Would it stop regional airports from growing? Not necessarily, but it might well mean slower growth than otherwise would be the case and airports not reaching their full potential.
I accept that for the likes of Teesside, Liverpool and Sheffield, new links to LHR would be beneficial. But which Northern airport(s) do you think could likely be adversely affected by their gain?