Gwynfor Evans belongs to an exclusive club of people who got the better of Margaret Thatcher. Incensed by her going back on a government commitment to set up S4C in 1980, he threatened to starve himself to death. It provoked a rare u-turn from the ‘Iron Lady’.

For such a determined campaigner on issues of language and cultural identity, Gwynfor Evans came from an unlikely social background. The son of a department store owner in the southern docks town of Barry, he didn’t learn Welsh until he reached adulthood.

It was at University in Aberystwyth that his politics crystallised. He set up a branch of Plaid Cymru, then a fringe party most identified with the campaigns of direct action advocated by the writer and academic Saunders Lewis. Like Lewis, Evans was a pacifist who refused to serve in the Second World War.

In 1945, he became party president and threw himself into the campaign against plans to flood the village of Cym Celyn near Bala in order to provide water for Liverpool. The campaign highlighted a growing threat to the survival of Welsh-speaking communities and of the language itself.

His finest hour came in 1966 when a parliamentary by-election was called in Carmarthen. Gwynfor Evans and Plaid Cymru came from nowhere to win a sensational victory.

Carmarthen signalled that Plaid was now a political force to be reckoned with. A year later the Labour government passed the first Welsh Language Act. While failing to impress most campaigners, it nevertheless provided for the use of Welsh in law courts and public administration. Another act, creating the Welsh Language board, followed in 1993.

According to the 2001 census, the number of Welsh speakers has now increased after centuries of decline. Gwynfor Evans can claim a large slice of the credit.