OK, so who's going to own up to chucking plastic wrappers and drinks bottles and (most oddly) beer cans around while out mountain biking? The guy insists he's seen this, and the drinks bottles in the hedgerow line has been used before I think.
Certainly it's not something I've ever seen, nor can I understand how it would happen – a can of lager is something I'm very unlikely to put in my backpack (though a pint of Lord Marples at the Cricket Inn might go down well after Blacka Moor), and my drinks bottle definitely doesn't get thrown away each ride.
Does this happen, or is the guy mistaking local yoofs from Totley for 'mountain bikers'?