Hello Leo,
Shame on me, a Scot, for not recognising Edinburgh Castle on the back-drop of your photograph. Not used to seeing the Castle from that angle. Looks so different from the usual view from Princes Street. (I can see the Castle, high on it's rock, from my street on the opposite side of the Firth of Forth. Local saying is, "If you can't see the Castle it's raining. If you can see the Castle clearly it's going to rain")
Anyway, Edinburgh Castle is another point in favour of his uniform being the Royal Scots. Dress uniform? Not likely to be a piper if he's from Yorkshire! But then, never assume.
Regards, Dod.