Another nice shot Alf.
Is he a "reptile man", ive never heard of him, to be fair, why should I have!
Anyway, back to your Adder, the blue hue to the belly/lower body scales, suggests that she is on her way to sloughing/shedding her skin(hence her darker appearance). Once she "sheds" she will then look her best(colouration wise). If she is constantly sighted basking in the same area, even if she is disturbed, she then returns to bask, then there is a good chance she is gravid. Gravid females will not hunt/eat at all, they spend the whole time putting all their energy, into their unborn. Females don't mate/give birth every year (it takes too much out of the snake). If she was not gravid, she would hunt/feed, therefore you wouldn't find her basking in the exact same area month after month, because she would cover a larger area(rather than stay in the same area) in the search for food. Imagine her coming out of hibernation around March(having not eaten through several months of hibernation) if she didnt breed the year before, then mated around April...no feeding until she gives birth (to live) around August/September...that's a long time without feeding, so after giving birth, she only has a couple of months to feed, before once again going into hibernation. Will she even catch a meal before Winter? who knows? That may be why these Adders(females) do not breed every year.
As I said, just my observations over the years, of monitoring these fascinating creatures...….........hell, I may be wrong, your snake might not be a female?!
Heres another one of my images...this pair were observed mating. Note their bright colouration, they had shed/sloughed their hibernation skin, before they paired up. cheers Paul.
Pair of Adders mating (uncropped). 15th-April-2014. by
Testudo Man, on Flickr