Plant was born in London on 29 April 1898, and died there on 19 April 1978. His father was a librarian. Plant was educated at the Strand School and then served in the British army in the First World War. Following the war he joined a mechanical engineering business, and by 1920 had been promoted to managerial rank. He then enrolled as an external student at the London School of Economics, initially with the objective of learning more about management and commerce. He quickly became interested in economics, and after taking his BCom in 1922, was awarded a BSc in economics in 1923. He had studied economics and economic history under Lilian knowles, Richard tawney and Eileen power, but the greatest influence was probably that of Edwin cannan.
From The Biographical Dictionary of British Economists in Oxford Reference.