I still don't get why Manston is never utilised more.
It's got a long runway, terminal and parking with not a very densely populated area.
They could at some expense, extend HS1 to Manston and improve the road. Improving the infrastructure wouldn't be cheap, but a hell of a lot cheaper than a whole new airport. At HS1 speeds on an express service you could be in Central London in just over half an hour.
You'll always have NIMBY's but most of the arrivals and departures would be over the sea, plus that area of Kent needs massive regrowth.