P D James is a writer of elegant descriptive prose and plots that the reader can interpret if s/he has the time to contemplate clues. Unlike other writers, whose crime solutions seem to come out of thin air, James gives the reader necessary information. Her characters are believable, if sometimes too good to be true or too true to be disbelieved - I'm thinking particularly of her career women, who are never shy or self-effacing. I have known a number of them in real life. The men are more gently handled: Adam Dalgliesh, for example, is such an unusual police officer - how many officers do you know who publish poetry? - that he remains in one's imagination long after the book has been put away.
I always check Amazon when I want a new British mystery, and in this case I have a three-in-one find, which makes for a heavy volume. But it's worth it!