The fourth of four cartoons designed and made for the window of a landing in the artist’s house in Rottingdean, Sussex. The windows (now in the V&A: C.623 to 626-1920) encapsulate the story of the Quest for the Sangreal (Holy Grail) and the failure of Sir Sir Launcelot (because of his adultery with Guinevere), Sir Gawaiane (because he fails to live up to courtly ideals), and Sir Galahad (because of his worldliness), and the achievement of Sir Lancelot, due to his purity of spirit.
For references to the windows, see Angela Thirkell ‘Three Houses’, OUP 1931 p. 123.