[1] Mann was born in Rockhampton, Queensland, to parents William Joseph and his wife Janet (née Low)[1] and was educated at Mount Morgan Boys Central School.

After being attacked by his opponents in the Assembly over the issue, he explained to the House that as a conscientious member of Parliament he was monitoring the illegal casino with a plan to exposing its activities when the police arrived.

In 1972, he handed back his life membership of the Labor Party after they disendorsed sitting members Ed Casey, Col Bennett, and Merv Thackeray.

[1] A generous benefactor of the disadvantaged, Mann gave a substantial part of his parliamentary salary to the poorer residents of Spring Hill during the depression of the late 1930s.

[1] During the motion-of-condolence debate after Mann's death, former Liberal and National Party member of parliament, Don Lane noted "he was fair dinkum to his mates.