British adder2

European adder (Vipera berus) at King Cobra Sanctuary - 29/05/2011

They are really beautiful snakes . I was lucky to see a juvenile on the Gower cliffs a few weeks ago , it was an unusual rusty/orange colour . Unfortunately by the time I got the camera out it was gone .

Are you sure it wasn't a Slow Worm? they are found pretty much all over the uk (I think), your description sounds a bit like an adult male. I saw one in cornwall on top of a compost heap

Female adders are very brown and rusty in colour unlike the males which are grey as shown in this photo, so it could well have been one.