But the matter must not reside simply according to the preferences of the MPs sitting in seats surrounding the airport. Boris Johnson was brave enough to look for an alternative on the east side, but perhaps there's another alternative. Not necessarily a total answer, but one that could partially solve this issue and also be an alternative answer to HS2.
The (partial) answer I propose is in VTOL (Vertical Take-off and Landing technology).
It's a little known fact that Britain was ahead of the world in the 1950s in this area of technology in relation to civilian use. Please look up Wiki for a description of the Fairey Rotodyne, which came close to success. Maybe now - 60 years on - the idea should be re-visited - there have been so many advances made in this time that I feel certain a concerted effort (and investment) should return results, at least for domestic and European travel.
Since the Rotodyne, the USA did not let go of the idea (neither did Britain, in the military Harrier development), and are still working on it for transportation purposes. But it does irritate me that we are now dependent on the US for all things new that require big investment. We had the technical people once, and I presume we have lost them to the US.
HS2 canot. surely, be justified at all, but I can see the need for a large VTOL service with maybe 4, 6 or 8 northward journeys per day, city centre to city centre. i.e. using a City Airport facility. And a similar VTOL service to major cities in western Europe.
Just think, no need for more runways than we have already, and the HS2 idea thrown where it should be - on the scrapheap. And couldn't a VTOL service be operational well before 2025?