Son of Cavan O'Connor, Irish tenor, BBC broadcasting star and variety artist,[2][3] and Rita, also a singer, maiden name Odoli-Tate, O'Connor is the grand-nephew of Dame Maggie Teyte DBE, Croix de Lorraine, Chevalier, Legion d'Honneur, the international opera soprano and interpreter of French song, and of James William Tate, songwriter, accompanist, and composer.

Educated at St Albans School and King's College, Cambridge, where he was an Exhibitioner and State Scholar, and won the James Essay Prize, O'Connor was President of University Actors.

He was taught at Cambridge by Professors Boris Ford and John Broadbent, with George Rylands as his Director of Studies, where O'Connor concentrated mainly on directing and writing plays.

He has also written and presented features for Radio 3, and acted as consultant on BBC 1 documentaries on Laurence Olivier and Pope John Paul II, appearing in the latter.

[6] In the early 1960s O'Connor wrote a short Daily Mail Charles Greville column, and then became television critic for Queen Magazine 1965–66, succeeding Sir Angus Wilson.

He is perhaps best known for his theatre biographies - including two of Alec Guinness; Paul Scofield; Ralph Richardson; as well as two books on William Shakespeare, these being his personal favourites and probably his most controversial works (see review citations in the Bibliography below for contemporary critical appraisal).

His 1997 biography of Peggy Ashcroft provoked a storm of anger and controversy within the British Press, with attacks from Harold Pinter, Lord Jeremy Hutchinson, and Labour politician Gerald Kaufman.