Speaking of Barbour I bought the same jacket @SpooPoker has for my Cocker Spaniel the other day, well, the dog version anyway. It has the same collar and everything...
I'm on the left in the Cucinelli and Incotex.
Ahh, the coat of Pitti.
I've had three of them now...and on all three it seems as if the sleeves are constructed pretty much like a trouser with cuffs, except that the excess fabric has been shaped so that the cuff doesn't extend all the way around. So basically, the answer is, make the sleeve a lot longer in the style of having buttons there, but then just roll it up and stitch in.