In 1954, Williams was appointed Lecturer in
Welsh History at
Aberystwyth University where he worked with another historian of Wales
David Williams. He left Aberystwyth for the
University of York where he was
Chair of
History from 1965 to 1974. He moved back to Wales in 1974, becoming
Professor of History at
University College Cardiff, where he stayed until his retirement in 1983. Throughout his career, Williams was known as an exciting lecturer, capable of drawing large crowds from across the university. After his retirement, he continued to write, but he focused more and more on television and film, presenting, with
Wynford Vaughan-Thomas, a 13-part series in 1985 by
HTV and
Channel 4 on Welsh history entitled
The Dragon Has Two Tongues. Williams was also a supporter of
Republicanism. He was later a member of
Plaid Cymru. And he praised the anti-monarchy book
The Enchanted Glass by
Tom Nairn. In 1983 he took early retirement from his chair at Cardiff and began making films with Teliesyn, an independent Welsh broadcasting company based in
Cardiff. In 1985 he had published his book
When Was Wales?, which followed his earlier study of the history of the Welsh working class) and which compatriot
Meic Stephens described as 'perhaps his most influential work.' Williams eventually moved from Cardiff to the village of
Dre-fach Felindre in
Carmarthenshire,
West Wales where on 16 November 1995 he died. ==Awards==