Bill and Jack Hooper built their 500 during 1947. The brothers ran a motorcycle shop in Sydney which specialised  in frame making and repair, their experience enabling them to build a proper space frame, unlike earlier Australia efforts. The car made its first appearance in 1948 and the Hoopers continued to improve the design through competing in '48 and '49, including a switch from Triumph TT to JAP power and revised steering.

They were also instrumental in inspiring Ron and Austin Taurenac to build his first car, the RALT, the Hooper car eventually being sold to Austin.

Jack Hooper enjoys a fag at Hawkesbury.

An article from Australian Motor Sport published in January 1950.

If anyone has any more details or photos, please get in touch.