I think Boris island these days is somewhere Mrs M will exile him too. St Helenas got an airport he can go there as governor.
FinnCapt. The problem with replacing LHR is that very few greenfield sites near the capital in London.
Those that look green on a map are
1 very hilly -not an ideal feature for airports
2 The very large one close to LHR to the west is a bit less hilly but belongs to Mrs Windsor the Queen and while in your neighbouring Nordics the royals might give up one of their numerous homes for an airport I don't see it happening in UK.
Remote sites with high speed rail cannot be used in Uk because the rail line planning takes even longer than airports and the train fare would be more than the plane fare most times.
So we are a bit stuck with dear old Heathrow which relatively speaking does have a decent piece of flat real estate right next to it only inhabited by working class people or foreigners neither of whom count in the British planning process. The problem is with the approaches which go over places populated by wealthy influential people who do count in the planning process. They are likely to object even though they live in West London because it is near to Heathrow.
Not much logic on infrastructure development in UK, we are not too bad at building it once started its getting the approval that takes literally a lifetime.
mid you Helsinki Vantaa has one useful feature in a world of air rage and unruly pax , it has a prison on site; is that right or an urban myth