When asked about influences, he most often names three past artists. First, Hieronymus Bosch, famous for those teeming, surreally fantastic landscapes of heaven and hell—including the Garden of Earthly Delights whose name was echoed in the Kirby collection In the Garden of Unearthly Delights. Next was Pieter Bruegel the Elder with his hauntingly detailed groups of warts-and-all Flemish peasants, not to mention the definitive portrayal of the colossal Tower of Babel which Kirby later spoofed in his movie poster for Monty Python's Life of Brian. Lastly was the muralist Frank Brangwyn (1867-1956), who made bold use of colour and monumental compositions on a large scale. Of all three Kirby said, 'I try to become more like these whilst contributing my personal viewpoint.'