I bought this a few years ago, when Otto Penzler was selling his collection through his bookshop, Mysterious Books. It's a review copy of an author I'd never heard of, but the short catalog blurb made it sound interesting: mysterious death on a train, unknown works by Gainsborough, Turner and Constable found with the body, along with a sprig of - you guessed it - sea lavender.
This is a mid-century mystery, and it suffered from the usual quirks of that age: instant, yet chaste, romance, and a complete disregard of the fair-play rules of mystery plotting. As such, the reader, by the end, is presented with a fait accompli in both the romance and the mystery's resolution, without having any idea whatsoever how the main character got there, although he does explain it all at the very end.
By today's standards, it's all a bit thin, naive and 2 dimensional, but I had fun with it nevertheless. It wasn't trying to be anything other than an entertaining mystery and, while I've read others that are greater successes, it generally achieved its goal.