Mate, don't take it as an offence, please, but in my opinion it's not a working dog you are talking about. "the dam is used for rats and has never been to ground" and "the sire was a stud dog and i do not know if he has beeen worked" means you have 2 pets which have a litter. Not many terriers would tourn away from a rat - but it doesn't make them a working terrier! If all the info you have of the sir is that he is a stud dog, it means (to me) that he wasn't worked much. If he would, you would probably hear about its work first.
Please don't take it hard, mate, I'm for you and not against