HiA thanks for replying, yes I do have a terrier and he would certainly see them off but they don't come when he is my garden. Rats do feed in the day time, I have seen them, but they mainly feed at night when all is quiet. Bait has been laid by professionals before Christmas and all is quiet at the moment but I do not want to be the cause of them returning as it is an expensive business. Being in a flat I have to consider the other residents. BTW I hate to tell you this but there is never just one rat.