Apollo is the Greek god of the sun, among many other things. On the Lower Hall ceiling, he rides across the sky in his golden chariot, drawn by four white horses. He is chasing away the mornig dew, which is represented by a cherub holding a water jar. 

Apollo's position on the ceiling, centred above King William and Queen Mary, symbolises the welcoming of the new day with their rule and bringing light to the royal couple.