Thank you.
If the solo photo is WW1, then he would have been 34 at the start of the war, already married over 12 years and with 6 children by then. He was Scottish, but I can find no record of his WW1 service on Ancestry, possibly because he had such a common name', but have messaged someone on Ancestry to see if he knows any more. The only image I have seen of him is as a much older man, and this photo could be him aged 34.
The 'family photo' is supposed to be Peter, wife, and child.
Peter served 1914 - 1920, a Private in the 2nd Kings Own Scottish Borderers
Married 1916, but first child not until 1924. Unless there was an earlier daughter we do not know about
Peter's brother Thomas looked so much like him they could have been twins.
Thomas served 1915 - 1919 Lance Corporal Seaforth Highlanders, and finally Acting Sergeant RAMC
Married 1917 and first child a son 1921
Again I think the photo is mislabelled and the mystery is who is the little girl?
Thanks again for your comments