In reply to Trangia:
Sometthing like this is desperately needed. The issue, I assume, is funding. I have proposed, in the past, a charge to climb at Harrison's & SF (and any other crags where agreement could be reached with the landowner). Someone could then monitor behaviour while collecting the money. I am informed, however, that the designation as CROW land prevents this. If true ( and I'm sure that commercial activity is not banned on CROW land) the BMC have probably acheived the amazing feat of being the first climbing organisation to oversee the destruction of a whole crag.