Knight of the Cloak
(The). Sir Walter Raleigh. So called from his throwing his cloak into a puddle for Queen Elizabeth to step on as she was about to enter her barge. (See Kenilworth, chap. xv.)
“Your lordship meaneth that Raleigh, the Devonshire youth,' said Varney, `the Knight of the Cloak, as they call him at Court.” —Ditto, chap. xvi.
Elizabeth, in the same novel, addresses him as Sir Squire of the Soiled Cassock.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894