Aces High keep one at Dunsfold; there are in fact two there at the moment but I don't know who owns the second one which is on the north side near the admin offices. The Aces High one is parked near the control tower (and the 747) where Mike Woodley (boss of Aces High) has his office.
John F; I've done some work in that tower recently (just Air Ground radio at the moment but we hope to get ATC licenced again soon) but it isn't the same without Harriers flying around, especially when they're flown by Hawker 97.