"the solitary Maid of Astolat"

 Elaine le Blank (meaning white or fair) of Astolat, also known as the Lily Maid, is a character from Arthurian legend. She fell in love with the knight Sir Lancelot, and when he refused to become her husband or lover she stopped eating, and eventually died. Her body, still in bed, was floated down the Thames in a barge to Camelot, bearing a letter in her hand to be read by Lancelot. Different versions of her story are told in Malory's Le Morte d'Arthur (which can be read here, starting at Book XVII, Chapter IX) and as part of Tennyson's narrative poem Idylls of the King (which can be read here). The story also inspired Tennyson's poem The Lady of Shalott (which can be read here).