Definition of "Derek"

"Do you think so? Her husband has an odd name - Derek Keppel. He is a musician - a violinist."

1895, The American Magazine, Crowell-Collier Pub. co.,1895. page 446

We do not entertain as much anymore because of Derek. (He produces strain. We have to pretend he doesn't.) I used to like him when I still thought he was normal. I was fond of him. I used to call him Dirk, and Kiddo, Steamshovel, Dinky Boy, and Dicky Dare. Till I found out what he was. Now it's always formal: Derek.

1974, Joseph Heller, Something happened, page 509

Frederick or Derek Boothby was in his late fifties, the son of a naval officer and a daughter of the Earl of Limerick.

2010, James Robertson, And the Land Lay Still, Hamish Hamilton, page 292