In reply to simes303:
As everywhere in England and Wales, you should have the landowners permission to sleep (actually it may only be to put a tent up, I don't think anyone really knows if sleeping on, for example, a public footpath in a bivvy bag would be considered trespass or not). But it seems that actually as long as you're not taking the p*** in some way, very few land owners or managers have a problem with wild camping/low profile bivvying
In the case of the Peak much of the high ground is National Trust managed, or Eastern Moor partnership managed. I've spoken to rangers and representatives from both who have said they have no problem with 'leave no trace' wild camping away from the roads. In fact it seems the only thing they are bothered by is people car camping and leaving rubbish, starting fires etc. I often don't go out until mid evening, so normally pitch my tent or role out my bivvy bag around midnight and then I'm up and away early morning. No one has ever had a problem with this. My understanding is this is a matter of civil law only, not of criminal law, so all a land owner can do is ask you to move on, so at worst you need to pack up and move on.]
It's a shame we can't have the same laws as Scotland south of the border, I got woken up by the most polite farmer ever back in August somewhere of the motorway in the Southern Uplands. He just said if we were going to camp on that spot of land for a few days would we park our car a bit differently so he could get up a track on to the moor. I explained we had stopped at midnight on our way down from Ben Nevis back to England and we would pack and be gone shortly. He said there was no rush at all and we should enjoy our breakfast! It was an immensely civilised interaction and really showed how well the Scottish outdoor code can work.