Bethel Calvinist Methodist Chapel in Tanygrisiau, Merioneth was established in 1838. In 1916 the church had 255 communicants but by 1935 the number of members had increased to 317 and then decreased to 233 by 1949. Included amongst the ministers that served the chapel over the years are R. Maurice Williams, Herbert Evans and Isaac Parry.
William Mona Williams was born in Llangefni, Anglesey in 1809, but moved to live in the Tanygrisiau area of Merioneth at the age of 23 in order to work on the Porthmadog and Ffestiniog Railway. In 1839 he was elected a deacon at Tanygrisiau Calvinistic Methodist chapel and in 1844 he emigrated with his family to America, only to return in 1846. He died in 1889.
From the guide to the Bethel Chapel Records, Tanygrisiau, 1843 - 1871, (Bangor University)
