King, politician and speaker of the House of Commons, was born at 91 Stapylton Street, Grangetown, near Middlesbrough. He was educated at Norton council school and Stockton secondary school, before going on to London University. He made a career in teaching and published widely on subjects as diverse as Homer, Macaulay, parliament, and Sherlock Holmes.
King was elected to the House of Commons in February 1950 and quickly demonstrated a flair for publicity. He arrived at the House of Commons for the first time wearing a cloth cap in memory of Keir Hardie, and made the first maiden speech of all the 1950 entrants. He was a very active back-bencher; within the Parliamentary Labour Party he stood with the right. He was a keen supporter of the Anglo-American alliance, making frequent visits to the United States, and he backed Hugh Gaitskell against unilateralism, but he was never a factionalist and attempted to remain on good terms with all sections of the party.
In November 1964, following Labour's return to office, he became chairman of ways and means and deputy speaker and in September 1965, he became the first speaker from the Labour benches. While no procedural die-hard, he was a traditionalist with a generally rosy view of established practices. Unlike many of his predecessors, he had no legal training but his headmasterly and avuncular style soon established his authority.