He's always been mounted by other dogs when at shows (you know who you are LOL), but now my bitch is coming into season he is being mounted by strange dogs while out walking and smiling hughley at the attention. 

Now I am sure he smells of the girl (not quite in season) and this is obviously a factor, I am concerned that he is showing much more of his feminine side just when he is being sought after as a stud dog.  I hope to use him on my girl - he was brought in to start our own line - and we will be travelling to very experienced breeder to facilitate the mating.

Has any one else had this sort of behaviour, I've never kept a stud before but always gone out for matings.

Just to add, I would take this as submisive behaviour and not quite what you would expect of a stud.  Any ideas?