I'm also a huge 'Adder' fan and have spent much of my time actively seeking out Adders to photograph. I have found quite a lot this year but I've also spent many outings searching with no success at all. Every now and then I have crept right up on top of one without seeing it until I was virtually standing on top of it. Usually they flee long before I get that close but occasionally one decides to stay still hoping to evade capture using its camouflage. I can see how they could be accidently trod on.
Please check out my Adder photos at:
www.jasonsteelwildlifephotography.yolasite.com