1966 Carmarthen by-election

Gwynfor Evans became the first Plaid Cymru member of parliament on July 14, 1966, winning by 2,436 votes in the contest that followed the death of Labour MP Megan Lloyd George. One seat in west Wales did not change the arithmetic at Westminster, but it changed what Welsh nationalism believed was possible. The result is treated as a seminal moment for the movement, and it sits at the start of the road that led to the Welsh Assembly in 1999.