Blackley was born in Masterton in 1953. He studied art history at the University of Auckland, graduating Master of Arts with first-class honours. During his time at the University he was a member of the Auckland Gay Liberation Front, describing himself as a "radical gay" who believed it was "too late for liberalism, because gay means more than just who you screw - it's a whole lifestyle." His 1978 master's thesis Writing Alfred Sharpe was a study of the painting and writing of the 19th-century landscape artist Alfred Sharpe.
