The Attenbury Emeralds. Perhaps too close.
I read Dorothy Sayers' Lord Peter Wimsey series when I was a teenager enthralled by Golden Age mysteries. Sayers' mysteries were always less whodunit than howdunit. How did the one of the small group of suspects (the guilty one being easy enough to guess for any self-respecting mystery fan) manage to commit the crime? Another notable aspect of the series was the reliance on dialogue. The books read more like plays with very little non-spoken exposition which means that characters have to deliver often tremendous amounts of background information in the guise of witty repartee. It can get on your nerves.
What can really get on your nerves is Lord Peter himself. If you didn't like the original series you won't like this book. Sure Lord Peter is married with children now but that's never been a very convincing arrangement. Anyone who read the first Wimsey books would be forgiven for assuming that the monocled son of a duke was Out, Loud and Proud. (He still seems better paired with the loyal Bunter but I guess Harriet is a bit masculine so I'll play along.) Walsh tries to update the series by referencing the changes in society - they don't eat in the formal dining room now! - which is fine in small doses.
But she takes is too far. How far? Somewhere around page 80 Walsh blithely mentions that sometimes Bunter the butler and wife sometimes sit down to dinner with the Wimsey family. I'd sooner believe that Harriet and Peter were committed Maoists.
The story is a bit blah. Starting out by having Peter recount his famous first case might not be a bad idea but its told in dialogue form with Harriet making witty comments and Bunter chiming in lugubriously to add an important detail and Peter losing the thread in his usual slapdash way.
It made me want to smack them. Yack, yack, yack. By page 40 I was praying for a murder. By page 50 I was willing to settle for the delayed detonation of a World War 2 bomb somehow left unnoticed in the Wimsey living room. Instead they went for a stroll to look at flowers while Peter kept telling the story and no one emerged to drown them in the Serpentine. There is eventually a murder which let's Peter and Harriet do their stuff: solve the murder while bouncing bon mots back and forth. The Wimsey family encounters a few significant developments, too, which does surprisingly little to dampen the witty repartee.
In summary, I didn't enjoy this book. Walsh is a talented writer but Lord Peter is best left in the inter-war years where class consciousness explains why no one throttles him and everyone can pretend that he isn't as gay as a spring day. If you're a huge fan of the Wimsey series this book might be for you. If you've never read any of Sayers' books then read a sample chapter first. Without the back story this might be an enjoyable mystery.