The Missing Shade Of Blue by Jennie Erdal (whose memoir Ghosting: A Double Life is featured here) - a philosphical thriller set here in Edinburgh, this is "moving, witty and wise, a compelling portrait of the modern condition, from the absence of faith to the scourge of sexual jealousy and the elusive nature of happiness."
Blue Remembered Hills, Rosemary Sutcliff's autobiography, "a record of the growing up and making of a writer ... full of humour, affection, joy in people and the natural world, and the kind of deep understanding that can come out of hard experiences."
Songs of Blue and Gold by Deborah Lawrenson. Another Cornflower favourite, this is a highly perceptive, absorbing novel based on the life of Lawrence Durrell (post here, and ignore that cover which really doesn't do it justice).
Girl in Hyacinth Blue by Susan Vreeland - "a gem of understated complexity", "an evocative masterpiece" about the lives and loves of those who have owned a Vermeer painting. Have you read it? I've had it on my wish list for ages as it sounds excellent and very appealing.
Any more blue books to recommend?