McLean was profoundly influenced by the work of Jan Tschichold, the German typographer, and he visited him at his home in Switzerland shortly before the outbreak of the Second World War.
From 1943 he was attached to Combined Operations Pilotage Parties, involved in daring explorations on enemy beaches in small craft in northern France.
By 1958 McLean was ready to move to a smaller concern, going into partnership with Fianach Jardine and resuming general design work.
McLean was of the opinion that the design and layout of magazines was of crucial importance and significance in the pre-television era, and this work became known as a practitioner's manual for those in the profession.
McLean continued as a practising typographer, and was called upon by well-known British journals and magazines, such as The Observer's weekend review, The Economist, New Scientist and The Twentieth Century.
Ruari McLean was Typographic Adviser to HMSO 1966–90, and much involved in assessing graphic design courses at art colleges all over Britain.