British peers and courtesy titles of grandsons when the heir dies

British peers of the higher ranks tend to have lower, subsidiary titles that they were promoted from or otherwise obtained. So a Marquess of X might also be Earl of Y, and Baron of Z.

According to my understanding, his eldest son gets to call himself Earl of Y (or Lord Y), and his eldest son gets to call himself Baron of Z (or Lord Z). But what happens if the Earl of Y dies in a tragic gardening mishap? Then the succession to the Marquessate moves over to the Marquess’s second son. Does the first grandson now have to give up using the title Lord Z? Or does he get to continue using it in a way similar to how former U.S. Presidents are still called Mr. President?

I’m curious about this situation because until I thought about it, I didn’t think it was possible to lose a title once you were entitled to start using it. And I don’t recall ever reading about such a situation in any novel, or anywhere else.

BTW I do know that titles and privileges can be lost for certain infractions or failure to measure up to the standard behavior expected of peers, and I read once of a certain new peer, in the 18th century, whose letters patent were withdrawn when it was clear he didn’t have the means to live the life a peer was expected to lead. But those are different situations from what I’m asking about here.

No – succession moves to the oldest son of the oldest son, so I suspect that Lord Z becomes the Earl of Y, and his uncle (let’s call him Lord A B, where B is the family surname) remains just Lord A B.

I see. So as long as the grandson by the eldest son exists, the succession will go to him eventually. But if there is no grandson yet, and Lord Y dies, then Lord A B would become Lord Y, and the heir apparent to the Marquessate, right?

Yes. See the details of Robert Gascoyne-Cecil, 3rd Marquess of Salisbury for an example. He was the second son of the 2nd Marquess of Salisbury. His older brother was the heir, and took the courtesy title of Viscount Cranborne. This older brother died before his father, and thus the second son, Robert, became entitled to the courtesy title Viscount Cranborne, which he held until succeeding to the marquessate on his father’s death in 1868. He went on to become Prime Minister.

Of course, now if the grandson were to also die in a tragic gardening accident, then Lord A B would presumably become Lord Y.

Which is presumably the reason that uncles menacing heirs is such a time-worn plot device. However, since peers in Great Britain lost most of their jurisdiction and special powers, that sort of thing doesn’t seem to happen anymore.