[2] He was educated at Falkirk High School and the University of Edinburgh where he was the Vans Dunlop Scholar in Mental Philosophy and Muirhead Prizeman in Civil Law.

[2] He was particularly effective as a defence counsel in criminal cases, and was regarded as the best advocate before a jury since Sheriff Comrie Thomson.

[3] He worked with Sir Arthur Conan Doyle and others to secure the release of Oscar Slater, the victim one of the most notorious miscarriages of justice of the early 20th century.

[4] An unsuccessful Liberal candidate for Clackmannan and East Stirlingshire in November 1922 and December 1923,[5] he joined the Labour Party and contested The Hartlepools at the October 1924 general election[6] and Glasgow Central in May 1929[7] — where he reduced a Unionist majority of nearly 6,000 to only 627.

[8] He was appointed as Lord Advocate in June 1929[9] serving in the Second Labour Government alongside Sir William Jowitt, the new Attorney General for England and Wales whose defeat at The Hartlepools in 1924 was attributed to Aitchison's drawing votes to the Liberals.