Background. The pose traces back to classical times – Aeschines, founder of a rhetoric school, suggested that speaking with an arm outside one's chiton was bad manners. The pose was used in 18th-century British portraiture as a sign that the sitter was from the upper class.
Yawn...
Zzzzzzz.......
Why do the royals put their hand in their jacket?
So that the blood doesn't show.