Thanks so much both of you- you've no idea how much it means to me to finally have this off my chest to an extent and to have had understanding responses. It would be a relief just to know I may not be completely in the minority with this kind of fantasy and that there may be a natural psychological cause behind it. It's been the whole business of keeping it to myself that's caused so much anguish, so finally letting that out is weakening the anxiety somewhat and I am seeking out a therapist, ideally someone with experience of both OCD and Autism sufferers, who will help me understand this thing. Thanks so much for your support, I'm amazed at the friendly atmosphere on these forums.