Thornhill's ceiling in the Queen's Bedchamber at Hampton Court is in the style of the expansive and exuberant interior decoration of the early 18th century, and tells the ancient myth of Aurora's abduction of Cephalus. The curtain of night is drawn back just as Aurora, goddess of the Dawn, attempts to entice Cephalus into her chariot. Her aged husband, Tithonus, lies asleep beneath a blanket of stars, and Procris, wife of Cephalus, rests in the lap of Morpheus, god of Dreams. The myth is not a straight-forward tale of marital infidelity, but a moral extolling the virtues of trust and loyalty in marriage, an appropriate theme for a royal bedchamber. This theme is then connected to the virtues of the new Hanoverian dynasty by the four portraits of three generations of the royal family surrounding the central scene: George I, Prince George and Princess Caroline and their eldest son Prince Frederick. These important early portraits, preceding Godfrey Kneller's official formal portraits of the Prince and Princess of Wales of 1716, are flanked by various allegorical figures and symbols, alluding to the proclaimed virtues and patronage of the new royal dynasty.
Thornhill won the commission to decorate the Queen's Bedchamber in 1715. he was already on his way to becoming the leading English artist of his day, famed for his work at St Paul's Cathedral in London, and the Painted Hall at the Royal Naval Hospital in Greenwich. He became the first English-born artist to be knighted in 1720.