Good afternoon,
I would agree on the bugle horn above shoulder titles but that would be light infantry. Cameronians did have a bugle horn as part of their badge, it was surmounted by a wreath with a star within it. It came from the 90th foot when amalgamated in 1881.
I would also expect to see tartan trews or kilt for Scottish regt.
I would agree pre war because of the regtl insignia being on the uniform but post 1908 because he has a web belt. Brought out that year to relace the old leather slade wallace equipment.
Most regular soldiers would have their own swagger sticks for walking out. Either purchased or homemade, they were regarded as a status symbol when walking down the street. Stick under one arm, lady on the other. Also made a handy weapon for the unarmed soldier returning to barracks after a few drinks.
John915