Vine in The Europeans, states that Joseph Mann also made the hibiscus brooch presented to QEQM by the Commonwealth of Australia in 1958.
It was designed by Ross Allan to represent the native Queensland hibiscus. The initial design incorporated 2 large black opals; however, the opals were rejected by Clarence House and the rubies substituted.
According to the National Gallery of Australia's website Ross Allan was born in Sydney in 1930. He was so young to have been selected to design the jewellery. What an amazing talent!