He contested the 1968 Caerphilly by-election, where he came close to unseating Labour in a safe seat, and became the second Chairman of Plaid Cymru in 1970, a post he held until 1976; when he became vice president of the party. He was responsible for policy and research in the party for many years.[2]
He stood down as an Assembly Member in 2003 to work on a research project to study the inner workings of the sun from the observatory near the North Pole. In 2001, he was voted Welsh Politician of the Year, and he was being pressured by former colleagues to become the next president of his party, following the resignation of Ieuan Wyn Jones as president. Shortly after standing down from the Welsh Assembly he suffered a heart attack while visiting a massage parlour in Cardiff[3] and was pronounced dead shortly afterwards.
