After a pupillage with Stanley Rees at 1 Crown Office Row,[2] McCowan specialised in criminal, property and personal injury law, practising in London and on the South East Circuit,[1] and became noted for his skill at cross-examination.
In 1971, he became a Recorder,[2] He became a Queen's Counsel (QC) in 1972,[3] and leader of the South Eastern Circuit in 1978,[4] having been appointed Deputy Chairman of the East Sussex Quarter Sessions in 1969.
[5][6] On 2 June 1981 he was appointed to the Queen's Bench Division of the High Court of Justice,[7] and received the customary knighthood the following month.
[1] In 1985 he presided over the case of Clive Ponting, a British civil servant who had been charged with violating section 2 of the Official Secrets Act 1911 after leaking documents about the sinking of the ARA General Belgrano.
[2] The same year he was made Senior Presiding Judge of England and Wales, a position he held until ill-health forced him to resign in 1995.