After serving from 1941 to 1945 in the Royal New Zealand Air Force during the Second World War he returned to a clerical position with Lands and Survey and on 9 May 1950 he was appointed as a Section Clerk at the department's head office in Wellington.

[4] He began working at the New Zealand Parliament on 14 June 1954 when he was appointed as Clerk of the Journals and Records within the Legislative Department.

The memo recommending his appointment quotes the Public Service Commission's view of him as being an "able, conscientious and energetic worker, who is respectful, bright and obliging, and whose claims to advancement are well above the average".

[6][7][8] He graduated with a bachelor's degree in law from Victoria University of Wellington (VUW) in 1957 and was admitted as a Barrister and Solicitor in 1965.

[15][16] In the 1985 New Year Honours, Littlejohn was appointed a Commander of the Order of the British Empire, in recognition of his services as Clerk of the House of Representatives.