Shot one
While I agree with you that the UK needs more airport capacity in the north this does not take away the need for one very underused runway in the south, after all the blocking of a runway at Gatwick disrupts air traffic in the whole of the UK as diverted aircraft cause further congestion at other airports.
If you think keeping Manston open is a political bribe I would sugest it is a poor one and the bribe money would be better spent on other projects, as a diversion airport for the major London airports it is good for preventing disruption from Manchester southwards......... The only problem is that people don't see the disruption that has not happened due to this sort of investment so politically it is a poor investment.
The cost of keeping Manston open should be the responsibility of LHR, LGW & STN, after all it is these airports that send most of the disruption oop North when they have a problem.