Editing Plaid Cymru (section)

===1970s===
In the [[1970 United Kingdom general election|1970 general election]], Plaid Cymru contested every seat in Wales for the first time and its vote share surged from 4.5% in 1966 to 11.5%. Gwynfor Evans lost Carmarthen to Labour, but regained the seat in [[October 1974 United Kingdom general election|October 1974]], by which time the party had gained a further two MPs, representing the constituencies of [[Caernarfon (UK Parliament constituency)|Caernarfon]] and [[Merioneth (UK Parliament constituency)|Merionethshire]].<ref>{{Cite web |date=2015-05-08 |title=UK General Election results: October 1974 [Archive] |url=https://web.archive.org/web/20150508153624/http://www.politicsresources.net/area/uk/ge74b/i04.htm |access-date=2025-05-16 |website=web.archive.org}}</ref><ref>{{Cite web |date=2015-05-08 |title=UK General Election results: October 1974 [Archive] |url=https://web.archive.org/web/20150508153653/http://www.politicsresources.net/area/uk/ge74b/i14.htm |access-date=2025-05-16 |website=web.archive.org}}</ref>

Plaid Cymru's emergence (along with the [[Scottish National Party]]) prompted the Wilson government to establish the [[Kilbrandon Commission]] on the constitution. The subsequent proposals for a Welsh Assembly were, however, heavily defeated in a [[1979 Welsh devolution referendum|referendum in 1979]]. Despite Plaid Cymru's ambivalence toward home rule (as opposed to outright independence) the [[referendum]] result led many in the party to question its direction.<ref name="McAllister 2001"/>

Plaid campaigned to leave the Common Market in the [[1975 United Kingdom European Communities membership referendum|1975 referendum]],<ref>{{cite web |url=https://digital.library.lse.ac.uk/Documents/Detail/in-memory-of-wales-to-be-killed-by-the-common-market/124971 |title=In memory of Wales to be killed by the common market |website=LSE Digital Library |publisher=[[London School of Economics]] |access-date=20 March 2025 }}</ref><ref name="auto">{{cite web |url=https://www.bbc.co.uk/news/uk-politics-33045935 |title=EU referendum: Parallels with 1975 |date=10 June 2015 |access-date=17 September 2019 |work=[[BBC News]] |archive-url=https://web.archive.org/web/20190416021343/https://www.bbc.co.uk/news/uk-politics-33045935 |archive-date=16 April 2019 |url-status=live}}</ref> feeling that the EC's regional aid policies would "reconcile places like Wales to their subordinate position".<ref name="williams-brexit2">{{cite web |last1=Williams |first1=Joe |date=22 October 2019 |title=The Welsh independence movement's Brexit stance risk alienating Leave voters |url=https://nation.cymru/opinion/welsh-independence-leave-remain-eu-europe/ |access-date=23 April 2022 |publisher=[[Nation.Cymru]] |archive-date=25 July 2021 |archive-url=https://web.archive.org/web/20210725214605/https://nation.cymru/opinion/welsh-independence-leave-remain-eu-europe/ |url-status=live }}</ref> Nevertheless, 65% of Welsh voters voted to remain in the EC during a [[1975 United Kingdom European Communities membership referendum|1975 referendum]].<ref>{{cite web |date=16 June 2016 |title=Europe Referendum 1975: How BBC reported Wales results |url=https://www.bbc.co.uk/news/av/uk-36474059 |access-date=23 April 2022 |website=[[BBC News]] |archive-date=23 April 2022 |archive-url=https://web.archive.org/web/20220423204934/https://www.bbc.co.uk/news/av/uk-36474059 |url-status=live }}</ref> The EC was incorporated into the [[European Union]] (EU) in 1993.<ref>{{cite web |date=7 February 1992 |title=Treaty of Maastricht on European Union |url=http://europa.eu/legislation_summaries/economic_and_monetary_affairs/institutional_and_economic_framework/treaties_maastricht_en.htm |access-date=23 April 2022 |work=Europa web portal |publisher=Activities of the European Union |archive-date=11 October 2011 |archive-url=https://web.archive.org/web/20111011055405/http://europa.eu/legislation_summaries/economic_and_monetary_affairs/institutional_and_economic_framework/treaties_maastricht_en.htm |url-status=live }}</ref>

At the [[1979 United Kingdom general election|1979 general election]], the party's vote share declined from 10.8% to 8.1% and Carmarthen was again lost to Labour, although [[Caernarfon]] and [[Merionethshire]] were held by the party.{{Citation needed|date=May 2023}}