McLean did his national service with the Royal Artillery and then joined the Metropolitan Police as a constable in 1951.
He attended the Royal College of Defence Studies in 1978 and the following year was promoted to deputy assistant commissioner.
From 1981 to 1983 he was deputy commandant of the Police Staff College, Bramshill.
He was the last officer to hold this post before the Metropolitan Police was reorganised in 1985, when he became Assistant Commissioner Territorial Operations (ACTO).
He was awarded the Queen's Police Medal (QPM) in the 1981 Birthday Honours[1] and appointed Commander of the Order of the British Empire (CBE) in the 1988 New Year Honours.