Steve Hardy was three weeks old when he was abandoned by his mother in the ladies' room of the Civic Theatre in Haymarket three days before Christmas.
As a baby he was charged by the police with being negligent and destitute, which Mr Hardy, now 64 - who was known then to officials as S.Hardie - still finds ''offensive''.
Mr Hardy now wants to find the woman who left her baby wearing a newly knitted shawl, matinee jacket, dress and singlet, most neatly labelled with his name S.Hardie. Other tags had been ripped off and dumped in a bin.
According to the police report, little S.Hardie was in good health and appeared well cared for when he was discovered by two girls at about 5.30pm on December 22, 1949.
''The mother had apparently left a tin of Lactogen and a feeding bottle and a small glass measuring tube which was wrapped in a bundle of clothing,'' a constable reported. ''The baby seemed to be in quite a clean condition and the clothes on it appeared to be new.''
Mr Hardy does not want revenge or recriminations, just a resolution to the mystery.
''If I had a wish, it would be for her to know I made it,'' Mr Hardy said. He knows finding his birth mother is a long shot as she would now be about 85.
Getting to this point has been a long journey for Mr Hardy, who is an artist and runs a karate school in Ballarat, Victoria, where he lives.
Mr Hardy grew up as Ray Cooper in Belmore, Sydney. It was not until he was in his mid-20s, after his elderly adoptive parents Reginald and Elsie Cooper had died, that he discovered he had been adopted. Angry, bitter and suffering from the chronic asthma he has had since a child, Mr Hardy learnt from a great aunt that he had been left in a Sydney theatre and cinema that was popular with high-kicking showgirls of the time.
''She told me I had been found in a picture show in Sydney,'' he said. When he told people, some would laugh with disbelief.
Until a few years ago, Mr Hardy thought his mother had dumped him because he was ill. ''I had a filthy attitude and a fairly large chip on my shoulder in my 20s,'' the father of six said. ''I knew I was sick and I knew I was adopted.''
He was so angry with the world that in his 20s he changed his name by deed poll from Cooper to Hardy. While nobody had ever told him he was adopted, he remembered glimpsing documents hidden in a drawer along with his mother's coin and stamp collections.
It was only recently that he realised his mistake: his birth name had been Hardie, not Hardy.
Eight years ago, Mr Hardy was refused a passport to go to Japan as the coach of the national karate team because nobody knew where he was born. That prompted him to hire an investigator. She found documents proving Mr Hardy's birth mother - presumed to be a young woman with fair hair wearing a red coat who was seen at the theatre - had left her baby in good health.
As a young man, he had thought he must have been ''mistreated by my mother. I thought whoever left me there, or abandoned me or put me up for whatever, mustn't have been a good mother.''
When he read the paperwork, he realised he had been in good health when abandoned. He believes the severe asthma that often kept him out of school had been caused by mistreatment at Myee Children's Home, where he spent the first year of his life. The paperwork relating to this period has disappeared.
He now thinks that his mother must have loved him, but was forced to abandon him.
''I was found three days before Christmas. I would suggest that my birth mother's family had Christmas functions and needed to get rid of the baby before that event.''
Because there was no record of where he was born, the location of the theatre was chosen as his birthplace. ''On my passport, it now reads Steve Hardy, born in Haymarket.''
Mr Hardy's six children, two of whom are doctors, have encouraged him to search for his birth mother. His daughter Megan Hardy, who is training in paediatrics at the Royal Children's Hospital in Melbourne, says her father's recent discoveries have ''unearthed all these emotions, and made him more emotional, quite reflective''.
His childhood has affected his parenting. ''He has very much taken on the role of the protector and the provider in his role as a father, partner and coach,'' Dr Hardy said. ''He doesn't want anyone close to him disadvantaged in any way.''