* Mr Garnett is David Garnett, son of translator Constance Garnett. At the time of the publication of The Common Reader, David was running a bookshop near the British Museum and had received a lot of acclaim for Lady into Fox, a novel in which a man's young wife turns into a fox. It's one of those odd books that keeps popping up on the periphery of my reading, which means I really ought to give it a try. I see that the edition I've linked to is in the Collins Library series from McSweeney's, which is a very good sign.
** Mr Masefield, whom you most likely were more quick to identify, is John Masefield, author of, among other books, the children's classic The Box of Delights.