Peter Ritchie Ritchie-Calder, Baron Ritchie-Calder (1 July 1906, Forfar, Angus - 31 January 1982, Edinburgh) was a noted Scottish author, journalist and academic.
Calder first worked as a journalist in Dundee and Glasgow, where he became noted as a socialist and peace activist; as Science Editor of the News Chronicle, he wrote under the name of 'Ritchie Calder'.
After moving to London before World War II, he accepted an appointment as the Director of Plans and Campaigns at the Political Warfare Executive branch of the Government, which was responsible for the allied war propaganda effort. He wrote propaganda posters and leaflets and speeches for allied leaders. He was a member of the 1941 Committee, a group of liberal politicians, writers and other people of influence in the United Kingdom. In 1941 he became popular with his book Carry on London, which described the effects of the German bombardment of London, Coventry and other cities in Great Britain.
After the war Ritchie-Calder returned to his former activities as a writer and specialised in internationalism, the peace movement and in the public understanding of science. He worked also with the United Nations and was President of the National Peace Council and of the Campaign for Nuclear Disarmament. He also worked for the News Chronicle newspaper as Science Editor.
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 Guys Hospital Medical School in London on Thursday, May 14, 1953 which resulted in an article by Ritchie Calder in The News Chronicle of London, on Friday, May 15, 1953, entitled "Why You Are You. Nearer Secret of Life."
Calder was an ardent peace activist and humanist. In 1955, Calder recorded and released an album on Folkways Records entitled, Science in Our Lives. In 1980 he was one of the signatories of A Secular Humanist Declaration, a statement of belief in Democratic Secular Humanism, issued by the Council for Democratic and Secular Humanism ("CODESH"), now the Council for Secular Humanism ("CSH").
He also taught International Relations at the University of Edinburgh, from 1961 to 1967. He was created a life peer as Baron Ritchie-Calder, of Balmashanner in the Royal Burgh of Forfar in 1966 and received the 1960 Kalinga prize.
Lord Ritchie-Calder was the father of science writer Nigel Calder (b.1931), writer and historian Angus Calder (1942-2008), mathematician Allan Calder and educationist Isla Calder (1946-2000). He was also the grandfather of travel writer Simon Calder.