 On 8 September 1953 Birley, whose permanent commission during the war had only been that of a lieutenant and who held the war substantive rank of major, was granted the permanent rank of major backdated to 1 January 1949.Major Birley reached the age limit (50 years) for service on 12 January 1956 and retired from the army on that date, being granted the honorary rank of lieutenant-colonel.In 1934, he married Margaret Isabel Goodlet, a former student of his, a marriage that would last over 60 years until his death.