The Approach Radar controllers for Heathrow, Gatwick, Stansted and Luton are at West Drayton and the London Area controllers are at the seaside. The Approach sectors expect to move to Swanwick next year (I think). The Heathrow controllers (of which I was one) moved to West Drayton about 12 years ago and the other airports followed suit (or were Gatwick there before us? Can't remember). There are no radar controllers at any of the above-mentioned airports.