I've seen that sporran badge before, but can't remember where now, and can't find it by googling.
Agree with James about the Seaforths buckle and non-A&SH sporran.
The photo can't be any earlier than 1919 because he's wearing his 1914/15 Star which, although instituted in 1917/18, wasn't actually issued until 1919-20.
Not sure what the other medal is supposed to be. If it's his Victory Medal, he's wearing them in the wrong order and you can put the date on to 1921-22. I can't identify the other medal ribbon on the right. ?MM?
If you'll forgive me - it looks like he may have just nipped into the local costume hire shop on his way to the photographer's to get a snap done with his newly received Star.
Where did the A&SH number 9591 come from? The only medal card I can find that matches your description is for 1194.
Adrian