Complex sentence: Following the death of Harry Hylton-Foster in September 1965, King, who had served as deputy speaker for ten months, became the Speaker of the House of Commons, he was the first person from the Labour Party ever to hold this position.
Split into simpler sentences: Following the death of Harry Hylton-Foster in September 1965, King, who had served as deputy speaker for ten months, became the Speaker of the House of Commons. He was the first person from the Labour Party ever to hold this position.