Quote Originally Posted by EagleJCS View Post
Doh! I knew that. I posted while under the influence of a medium grade fever and wasn't thinking clearly.

Actually, until recently (the last 5 years or so?) His Grace's family name is Montagu Douglas Scott (unhyphenated). Has been since 1810. The late Duke decided to return to using just Scott as his patronymic and encouraged his children to do the same. However, the current Duke uses the modern convention of using his title (Buccleuch) as his last name when signing correspondence. I believe his children are using 'Scott', though.

...
Not quite.

The convention---the rule set out by Lord Lyon---is that the chief of a clan must bear the clan's name as his surname, unhyphenated, unadorned.

When a peer, or even a Scots baron aka a laird, signs his name, he inscribes the territorial or other designation of his title, rather than his surname. Here, the surname is "Scott," but the legal and customary signature is "Buccleuch."