William Richard Thorpe AM was an English-born Australian singer-songwriter, and record producer. As lead singer of his band Billy Thorpe & the Aztecs, he had success in the 1960s with "Blue Day", "Poison Ivy", "Over the Rainbow", "Sick and Tired", "Baby, Hold Me Close" and "Mashed Potato"; and in the 1970s with "Most People I Know Think That I'm Crazy". Featuring in concerts at Sunbury Pop Festivals and Myer Music Bowl in the early 1970s, the Aztecs also developed the pub rock scene and were one of the loudest groups in Australia.

Sunbury Pop Festival or Sunbury Rock Festival was an annual Australian rock music festival held on a 620-acre (2.5 km2) private farm between Sunbury and Diggers Rest, Victoria, which was staged on the Australia Day long weekend from 1972 to 1975. It attracted up to 45,000 patrons and was promoted by Odessa Promotions, which was formed by a group of television professionals, including John Fowler, from GTV 9 Melbourne.