Just watched the NATS video (direct link here) linked from the above post
There are many detractors on other threads who love to take a dig at Luton at every opportunity often describing it as an airport on a hill. To those people it is worth looking at this screen shot from the tower showing the flat lands to the south of the runway. The airport might never end up getting expanded in that direction but the land is there so it will always be a possibility when Luton gets close to 18 million passengers.
As seen in the video the private jet community have made Luton the UK's busiest biz jet airport. Good to see at least they seem to like the place