Peak District Adders

I am new to the forum and this is my first post. I have had this obssesion of looking for adders for the past four springs as its the only snake I havent seen in the uk and it has been illusive to me untill last week.

I live in the peak district and apparently it has a good population of adders, but of course we never see them, any way I came across a hibernacula last week on a cool frosty morning but the sun was shinning, I was out pretty early and stumbled across one basking in the sun, I just sat and watched it's behaviour for a while then after around 10 more minutes another one appeared from the heather next to it I couldn't believe it to be honest. I decided to have a look around the area as they were obviously sited in this particular spot and found four all within a few meters of one another.

The siting proper made my day and I have been to the site every day since, just to see if anyone else knew about it and to keep an I eye on the place really. The one thing that has played on my mind since the first siting is why there? I wouldn't have thought to look in this particular spot as a rule of thumb and I wouldnt have put them to be there.

I was wondering if anyone else knew of any more populated areas in the peaks as I am pretty keen to find more and try and understand there behaviour, you can PM me as I understand the protection of these creatures and rightfully so,the last thing I would wont is locations giving out to the general public.  

Many thanks Chris