Over the years that I was with the Dartmoor National Park Authority I dealt with many. They are not all the same and in fairness, some left the site so clean you wouldn't know they'd been there. However they know the law and won't be threatened. I found that if you were honest with them, treated them like human beings and with respect, in the main they respected that. Yes you always get the odd ones. I served Enforcement Notices on some groups and usually they left on time. Again, in fairness, one young lady even rang me to tell me that they had left the site. They had and had left it clean. O