Hi Susan,
The 1968 electoral roll has:
Wheadon, Brian Garnet, 66 Tivoli Road, Accountant (Subdivision of South Yarra, Victoria).
He is also recorded as an accountant in subsequent electoral rolls. In 1994 he was living in NSW:
NB322/94—Re Brian Garnet Wheadon, 78 Sirius Road,
Bligh Park 2756, sales consultant (22.2.94)
Source:
https://trove.nla.gov.au/newspaper/article/246956557?searchTerm=%22garnet%20wheadon%22 It seems likely that he died in NSW some time after 1994, but deaths which occurred less than 30 years ago are not online. Burials are recorded and there is a possible death in 2021:
Name Brian Wheadon
Birth Date 5 Jun. 1944
Death Date 7 Jun. 2021
Cemetery Lakeside Memorial Park
Burial or Cremation Place Kanahooka, Wollongong City, New South Wales, Australia
Perhaps you have his date of birth which matches. Parents were married in 1941.
Christine