Kammala jumla mai zuwa: Ya shiga Plaid Cymru a 1973, bayan ya burge shi da yakin neman zaben Emrys Roberts a zaben Merthyr Tydfil. A shekara mai zuwa a 1974, ya fara aiki ga Plaid Cymru a matsayin jami'in bincike na majalisa. Ya kasance a cikin mukamin har zuwa Disamba na 1979; shekara ce mai wahala ga jam'iyyar, wacce ta fuskanci rashin nasara a cikin
Shawarar raba gardama ta Welsh da asarar kujerar Gwynfor Evans a babban zaben. Tare da raguwar kasancewar a Westminster jam'iyyar ba ta da bukatar manyan ma'aikatan majalisar kuma an kori Griffiths.