This design is the second of four cartoons designed and made for the window of a landing in Burne-Jones' 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).
This cartoon depicts Sir Gawaiane, asleep, failing to see the grail which is shielded by the angel turning away. The inscription below reads: HOW GAWAINE SOUGHT THE SANGREAL AND MIGHT NOT SEE IT BECAUSE HIS EYES WERE BLINDED BY THOUGHTS OF DEEDS OF KINGS