He was a younger brother of Sir Archibald Edmonstone, 1st Baronet of Duntreath and Newton.
He rose to the rank of lieutenant colonel and served variously in Geneva, Siena, Paris and Dublin.
Due to the age of Earl Stuart's youngest child this role would have ceased by 1775 or before.
[4] In 1745 he (or his family) entertained Bonnie Prince Charlie for an evening at Old Newton House.
Old Newton House still exists and is lettable as a holiday home including a "Hume Room".