I am reading all of Graham Greene's works in chronological order during this pandemic (you have to do something!) and I'm throwing in to my reading order a few of the vast array of books written ABOUT Greene. Samuel Hynes has put together a helpful collection of essays written about Greene. I found the ones by W. H. Auden, Evelyn Waugh and Richard Hoggart most interesting. George Orwell's essay seriously attacks Greene, declaring frivolous Greene's "cult of the sanctified sinner." If you are a serious Greene fan, you'll enjoy this collection.