At 6.50 p.m. on 31 August 1997 a plane touched down at Northolt Airport. It was a lamentable and dismal evening. Prince Charles, wretched and ghastly, accompanied the coffin that carried the body of his former wife Diana. Watching from the wings was Tony Blair. The nation mourned. And Northolt Airport did the job it has done so often — being the receiver of the great and the good and the bad, dead and alive.