After the war Calder returned to his former activities as a writer and specialised in internationalism, the peace movement and in the public understanding of science.
Sir Lawrence Bragg's original announcement of the discovery of the structure of DNA was made at a Solvay conference on proteins in Belgium on 8 April 1953 but went unreported by the UK press.
He then gave a talk at Guy's Hospital Medical School in London on Thursday 14 May 1953, which resulted in an article by Ritchie Calder in the News Chronicle on Friday 15 May 1953, entitled "Why You Are You.
[2] He was Montague Burton Professor of International Relations at the University of Edinburgh from 1961 to 1967,[3] and received the 1960 Kalinga Prize for the Popularization of Science.
While employed at the Foreign Office, Calder was appointed Commander of the Order of the British Empire (CBE) in the 1945 New Year Honours.