Darcy,
Wow! Thanks for the prompt reply. The son, Robert, is my gggrandfather. I have been searching for any info on him for a couple of years. Unfortunately, he was the first person I started with when doing genealogy. Not a good choice. I know very little about him - here's what I do have (this is all about the son, Robert)
Robert David JOHNSTONE married Sarah Ann Taylor in Parish Church, Tynemouth, on Dec. 25th 1876. He is listed as being 25, a bachelor, occupation Guard, living in Tynemouth, father is Robert Johnstone, deceased, Clock and Watch maker.
Robert and Sarah JOHNSTONE had a son, James William, born April 10, 1877, in Percy Main, Chirton, and Robert is listed as a Railway Guard.
Robert and Sarah also had a daughter, Anne Isabella, born about 1881, in Percy Main, Northumberland, per the 1881 census.
However, in the 1881 census, Sarah JOHNSON is living with her parents, William and Sarah TAYLOR, in Chirton, Percy, Tynemouth, with her two children, William and Anne, but no sign of her husband, Robert. She is listed as being married.
In 1887, Sarah JOHNSON married Mathew LACKIE. I have not received the marriage certificate on that one yet.
The only other info I have is a letter from a family member to my ggrandfather (William) commenting on the fact that his father had been around looking for him - and that was in 1908. Don't know if that was his father, Robert, or his stepfather, Mathew. The only "father" my ggrandfather ever mentioned was actually his grandfather William Taylor!
Unfortunately, with the names going back and forth from Johnson to Johnstone, I have been researching both. There are a lot of them! As I have no birth place for Robert, the son, it has made things very difficult.
Any thoughts you may have would be greatly appreciated. I was hoping that by finding a Robert Johnson, clock and watch maker, fairly close to where the son was married, I had hit the jackpot. Maybe not. Frustrating.
Thanks for all of your help so far!

Roberta