Tributes have poured in from colleagues and former reporters. Sydney Morning Herald chief investigative reporter Kate McClymont described Manning as "a colossus of Australian investigative journalism". Others called him "a fierce and loyal protector of journalists" and "the best boss I ever had", praising his "attention, care and infectious enthusiasm".
Manning was born in Sydney in 1945. He grew up between Bondi and Toongabbie after his parents divorced when he was young. He attended Waverley College. At 11, he had a letter published in the Daily Telegraph denouncing the Soviet invasion of Hungary. After high school, he worked as a copyboy at the Telegraph, his first job in journalism.
In 1962, Manning began an arts degree at Sydney University. Initially a fervent anti-communist, he tried to revive the dormant Democratic Labor Party club on campus and supported the Vietnam War. But his politics shifted under the influence of the university's Catholic chaplain, Ted Kennedy, who espoused liberation theology. Manning considered the priesthood but was inspired by Kennedy to "live your values of love and social justice in the world, don't hide in a church". As one observer noted, many grow conservative with age; Manning went the other way.