John was 48 in 1912 when he married his 2nd wife Mary Munro. I couldn't find John and his 1st wife Ellen in the 1901 Census either.
All I know is he died in 1926 Greenock, his son George R Moore was born 1892 Rutherglen, married Sarah Drummond in 1919 Greenock and died in 1955.
Just recently a cousin of my Girlfriends Mum passed away, but if George was an only child then how could this be? her Mums maiden name was Moore, and the relative that died was Moore so has to be from her Grandfathers side. I think this is a brick wall.