What Was Lost Was Lost" was the winner in the first novel category of the Costa Book Awards. O'Flynn received a £5,000 prize. It was short-listed for the overall Costa Book of the Year Award. The Costa Book Awards' judging panel, chaired by Joanna Trollope, praised the novel for "blending humour and pathos in a cleverly constructed and absorbing mystery." They described the novel as inventive, compelling, and poignant. "What Was Lost" was long-listed for the 2007 Man Booker Prize and the Orange Prize for Fiction. It was short-listed for the Guardian First Book Award. It won the Jelf Group First Novel Award
Dundee International Book Prize winning the 2015 prize with his page turner – "Devil Take The Hindmost" in which he brilliantly evokes the seedier side of interwar London. "Devil Take the Hindmost" was published by Freight Books in June 2016. Jessica Thummel was 2016 winner. "The Cure for Lonely" (originally titled "The Margins") is the coming-of-age story of Sam Gavin, a transman who moves from Kansas to San Francisco in the summer of 1989. It will be published in summer 2017. Dundee International Book Prize The Dundee International Book Prize bills itself as the UK's premier prize for debut novelists. It includes a £5,000