who was the Melbourne radio presenter whose first name was Bert?

The Melbourne radio presenter was likely Bert Newton. He began his career on Melbourne radio in 1952 and later became one of Australia’s best-known TV and entertainment personalities.

A second possible match is Bert Bryant , who worked for Melbourne radio station 3UZ as a racecaller and sport director. If you meant a general “radio presenter” rather than a racecaller, Bert Newton is the more likely answer.