Roy My great grandfather was James Kilgour Ainslie and was married twice. His first wife was Caroline Krummeck and they had 2 sons of whom I have no info except that they were born circa 1871 and 1872.
He had 2 sons and 4 daughters with his second wife and I have most of theit info.
There might be a possiblity that your grandfather could be one of his 2 sons with Caroline, but you have to get more info on him. What about a sertificate of baptism or a death notice?