Converting a tweed sport coat to a Braemar jacket

[vorpallemur]

Ah, the buttons were put onto the sleeves to prevent soldiers from wiping their runny noses, and I think the extra material that form the cuffs are to offer additional protection while on horseback from the leather bridal etc...

Coats with cuffed sleeves have historically had functional buttons. Unbuttoning the cuffs allows them to be rolled up, so you can do work without getting your sleeves in the work. Good quality suit coats stlll come with functional buttons, a feature often called "surgeon's cuffs", in memory of their purpose, even though the tailoring on modern coats sleeves makes it impossible to roll them up, even with such a cuff.