Edith Caroline Rivett (who wrote under the pseudonyms E.C.R. Lorac, Carol Carnac, Carol Rivett, and Mary le Bourne) was a British crime writer. She was born in Hendon, Middlesex (now London). She attended the South Hampstead High School, and the Central School of Arts and Crafts in London.
She was a member of the Detection Club. She was a very prolific writer, having written forty-eight mysteries under her first pen name, and twenty-three under her second. She was an important author of the Golden Age of Detective Fiction.
A clever premise, but much too talky. A large cast of characters, for a relatively short novel, and "investigative honours" are shared between the pros (Macdonald and his team) and the amateurs, who are not as cute and winsome as Lorac would like to think they are.
In this way, the mystery is spread pretty thin, by letting the growing cast of characters talk, talk, talk it over. There's a dispiriting moment, toward the end when Macdonald admits
Caroline Rivett's best novels balance the mystery with a strong sense of place and time: I think her novels set in the Lune Valley (Fell Murder) and Devonshire (Fire in the Thatch and Murder in the Mill Race) are her best, even if the mystery might be weak, because she really captures the setting, and places her characters in a real, evocative context. One of her London novels, Bats in the Belfry, has a very similar plot to this: it doesn't set the world on fire as a mystery, but it has characters who suggest real backstories and it conveys a wonderful sense of London, before the war -- a London that in a few short years would be changed completely.
Ask a Policeman doesn't have that saving grace: London never really comes to life, and the Bright Young Things who get involved in the rum goings on at Rosetta Tower are bland, and hard to tell apart. (Also, I'd say that their "jolly good, what ho" dialogue is about 20 years out of date, and feels like something out of a rip-off of a Noel Coward play.)
Which is a terrible shame, because when her heart was really in it, as in Fell Murder, Rivett could capture the voice of real people, and demonstrate a touching understanding of why people love the places where they live, and even why they would be willing to murder for it.