In reply to andyathome:
You need to be on some Peak crags (and also Almscliffe!) when the 'instructors' show up. Recently been grumbled at for wanting to lead a route and moving the pre-set top rope to one side. The 'instructor' said; "We were going to do that route in a few minutes, didn't you see our rope?" They had four ropes set up on the Ants area of Yarncliffe Quarry. I explained calmly that as there was no one actually climbing the route I had every right to climb it. Pre-booking by placing a rope was inconsiderate. I also pointed out that his van was completely blocking the gate, but he said "No-one ever wants to open the gate so it is not important" . Compare this with another experience, where the instructor was apologetic, asked what we were going to do, rigged his gear so that, as we moved across the crag, he kept his charges out of the way. A good time was had by all, no intolerance, the resting students watched us climb, asked intelligent questions etc. We chatted with the group, had a laugh, a much better experience for all concerned.
Many 'commercial' instructed groups appear to believe they have a right to do what they want at a crag, park where it suits (as they have big vans and need to keep their charges safe.) book routes well before they actually start to use them, and then set up an abseil down the most vulnerable routes (where they can scrape off the last vestiges of small rounded holds), as that is the place where they can't climb up. I heard the rude instructor mentioned above that the students should go into the trees if they needed the toilet!
Commercial groups making money from an area should at least have the courtesy to contact the owners for permission, and live by the rules and requests of that owner.