Identifying where soldier or officer served and time period

Hi all - I have an antique (or verging on antique) rolled gold locket of a young man in an official outfit. He is wearing a uniform and has a cap with what seems to be an emblem of five thistle leaves.
I think it's possible he was an officer maybe to do with aircraft or horses or boats rather than a foot soldier, as it seems more like someone in charge of a regiment of sorts.
I have googled a fair bit but haven't found any scottish hats that match, most of them also have tartan, but none match the thistle leaf design.
Thanks in advance.