I am doing a One Name Study of Cattanach and all its variants.My husband is directly descended from a George Catanach.
I have the following details on (maybe) your great uncle, John Roy Cattanach:
He was born 18 Apr 1890 in Fordwich, Ontario, Canada.He was employed as a cable splicer before joining up to fight in the First World War.His attestation record gives the following physical note:John had a tatto on his right forearm of the American flage and shield.On his left forearm, a heart and dagger.
Unfortunately, that is all I have.
Could you please send me what information you have.
If you need some help with your research, I am happy to do so.