Forget about a third runway at Heathrow; it's not going to happen within the next ten years and, even if it happens, it won't be a popular move.
Forget about a second runway at Gatwick. It's not going to happen within the next ten years and, even if it happens, won't be a popular move.
Don't even bother looking at Stansted.
Forget about HS2; it's not going to........etc, etc.
Why can't the UK take a leaf out of the Germans' book. They have two major international hubs. One in the south, Munich, and one up north, Frankfurt.
All this focus on Heathrow and Gatwick overlooks the fact that there is a well established two runway international airport "up north" in the UK. Why not use up some of the runway capacity at Manchester. You never know, it might obviate the need for more runways in the south east and blow HS2 off the rails.
Hat, coat and waiting for incoming.