Siân Gwenllian MS
Member of the Senedd for Arfon
Siân Gwenllian has represented the Arfon constituency in the Senedd since 2016. Re-elected in 2021, she secured 63.3% of the vote—more than any other candidate in Wales—doubling her majority. One of her proudest achievements is successfully campaigning for a new medical school for North Wales, based in Bangor within her constituency. Currently, Siân holds the Housing and Planning portfolio for Plaid Cymru (2024–). Previously, she served as the Lead Designated Member in the Co-operation Agreement (2021–2024) between Plaid Cymru and the Welsh Labour Government. During this time, she worked across 46 policy areas, helping deliver transformative initiatives such as: free school meals for all primary pupils, expanded access to free childcare, bold measures to tackle the housing crisis, reforms to create a more effective and representative Senedd.
Throughout the fourth and fifth Senedd terms, Siân has held a range of policy portfolios for Plaid Cymru, including Education, Local Government, Planning, Welsh Language, and Culture. She has also served as the Party’s Senedd Commissioner, Trefnydd, Chief Whip, and Deputy Leader in the Senedd. In 2024, she was appointed Director of Policy on Plaid Cymru’s National Executive Committee.
Siân was raised in the village of Y Felinheli, where she still lives. She attended secondary school in Bangor and studied at both Aberystwyth and Cardiff universities. Her professional background includes journalism with the BBC, HTV, and Golwg, as well as freelance documentary production. From 1997 to 2004, she worked as a press officer for Cyngor Gwynedd.
Her political journey began at the local level. In 2008, she was elected county councillor for Y Felinheli, serving for eight years. She held the Finance portfolio (2010–2012) and later became the Council’s Deputy Leader and Cabinet Member for Education, Children and Young People, as well as the county’s Small Business Champion.
Siân’s commitment to public service spans decades. At Aberystwyth University, she was Deputy President of the Students' Union. She has served as a school governor, chaired her local community council, and volunteered with numerous local organisations. A passionate advocate for women’s equality and the Welsh language, she has campaigned on these issues for over 45 years.
Siân is a mother of four. She raised her children as a single parent following the death of her husband, Dafydd, from cancer in 1999, when their youngest son was just three years old.
Contact Sian
T: (01286) 672 076
A: 8 Castle Street | Caernarfon | LL55 1SE
F: Facebook
