Yn 1800, cyrhaeddodd dau frawd, William a Thomas Casson ardal Ffestiniog o ardal y Llynnoedd, gyda'i ffrind William Turner. Roedden nhw wedi prynu'r chwarel lechi gyntaf a agorwyd yno, ac wedi'r ymdrechion cynnar, llwyddasant i greu busnes llewyrchus iawn.
In 1800, two brothers, William and Thomas Casson, arrived in Ffestiniog from the Lake District, with their friend William Turner. They had bought the first slate quarry there. From early struggles they turned it into a thriving business.