Title from item.
Drawing is one of 11 by Robertson that appear to illustrate stories from Una Ashworth Taylor's collection of fairy tales entitled Knight Asrael and other stories, published: London : Swan Sonnenschein & Co., 1889; Robertson was a friend of both Una Taylor and her sister, Ida Taylor, whose book Joan of Arc : Soldier and Saint was published with illustrations by Robertson in 1920; it is possible that Robertson's series of drawings were intended to serve as illustrations for an unrealized later edition of Una Taylor's book.
In pencil at lower left: The City of the Moon.
Drawing shows a little boy holding a lance and shield.