Hi again Annette,
That was a good call on John Watson and Mary Lawrie, I think. I looked at the other census records and in 1861 there is an Alexander Watson living in Peterhead who's parents are John Watson and Mary Lawrie. Living with his family is Robertson Milne who was Rachel Milne Watson's younger sister.
Mary Lawrie Watson's death cert shows her husband John Watson, shoemaker in Peterhead as deceased. Her son James is the informant. She is living with this family in 1861. In 1851 she is living with son Alexander and in 1841 with husband John and son Alexander and daughter Jane. I think this is going to be a case where I put them all together and say "probably" until I send for John Watson Jr.'s death cert from England. That will be a ways down the road!
These forums are a great help. I would have been chasing my own red herring around in circles some more without everyone's help!