'The Late Scholar' by the official continuer, Jill Paton Walsh. This is the fourth of her Wimsey mystery novels, the first ('Thrones, Dominations') was based on an outline for a late novel Sayers never finished. The second ('A Presumption of Death), set during the early years of WWII, may be the best, IMO, while the third ('The Attenbury Emeralds') has Walsh going back and filling in some of Wimsey's background. Although set in the late 1940s, it ranges over a thirty year period.
This new novel has most of the old characters coming in for at least a walk-on, and they are the most interesting part of the story. Wimsey as a personality is as formidable as ever for the most part, but the scholarly and the detective sides of his intellect seem faded. A few parts read as if Walsh has started a nice red herring for the reader, but then never does anything with it, and there were a few internal contradictions that some editor should have caught, and a few others an editor who knows the Wimsey canon would have.
Still, on the whole, it was well worth this Wimsey fan/scholar's time to read, and I'm sure I'll reread it often in the future.