>mountain bikes = tv show = money to NT <
Ahh, now I understand. In other words, the National Trust at Avebury = an incompetent fiscal plan = panic response allowing mountain bikes for a TV drama featuring said bikes whizzing up and down the ditches of a World Heritage Site = little signs on gateposts saying 'No cycling'. How silly of me not to have seen the logic behind all of that.
Now, on the question of how much money <i>you</i> spend on the upkeep of Avebury?