Judith Durham was the lead singer of the Australian band called The Seekers back in the 1960’s. I’d say their most famous song was Georgy Girl which everyone knows. It was even parodied on The Simpsons where Homer got to ride in a blimp.
They had a few major songs but I don’t think they managed to get higher than number 2 outside of Australia. Although they were the first Australian group to have a top 5 hit in Australia, U.K. and America.