I can see that mountain biking could do a lot of damage and should be discouraged in whatever way that works - initially by educating bikers about the heritage aspect of the sites.

I'd agree there is a major problem... I'm currently putting on some of last year's fieldnotes I never got round to and note that I bawled out a middle aged woman using The Whiteleaf Barrow (Bucks) as a mountain bike ramp.... that she was so shocked probably says all there is to say. How can we teach our children to respect our culture when adults - affluent middle and upper classes, at that - either don't have a clue or don't give a damn?

And as for the upland versions of these monuments - the mountain cairns.... don't even get me started!!!!