The RAF regt do more for public relations by allowing this than a lot of things the RAF do.
The Reds and Falcons at Llanidloes (small village smack in middle of the LFA) is another good example.
Best airshow me seen. (and I've been to a few)
Rumour has it that anything flying checks in with the ground controller (FAC) and gets given a "slot".
It prolly is a little stricter now but that is how it was done until recently.
I remember seeing a USAF F-111 dripping with snakeeyes on every hardpoint on his way to wainfleet go over the crowd at maybe 100'. You dont get to see that too often in a propoer airshow!!