AHA! That's why I'd never heard the phrase! I've only ever read pre-conquest and immediate post-conquest materials, as one of my primary interests is the (extremely fuzzy) border between Old and Middle English, followed by Early Modern Engiish to the English of the current day. High Middle English has always bored me, so I've never read the Arthurian legends, and I've only read Chaucer because I was made to read him in high school (and I hated it!).