This note contains spoilers for the book.

Eighteenth and last of the Lord Ramage novels. He finally gets appointed to something bigger than a frigate. He's sent to the West Indies, and does well, though nothing very spectacular. The admiral calls him back to base for orders. He finds the admiral over him to be intelligent and sensible. And the last line is "I still don't know what the admiral has in store for me." It doesn't sound, to me, like something intended to be the last book of a series!

Yes, a bit of web research says he was forced to give up writing for health reasons (loss of memory, apparently associated with a WWII spinal injury) in 1989. He didn't die until 1997.