1841 The 'cause' in Efail Isaf was started - a branch of Taihirion Chapel, Rhydlafar with the Rev Lemuel Smith as Minister.
"It was started in the ‘longroom' alongside the village tavern called ‘Carpenters' Arms'. The room stood separate from the 'Carpenters' at the side of the garden, where there were stairs to reach it from the outside". (Translated from the Centeneray Book 1941)
It was decided to build a chapel on the Celyn farm land.
1842 The foundations were laid at the start of the year. The Rev. Lemuel Smith died. Rev Levi Lawrence was confirmed as Minister.
1843 The chapel was built and opened.
1847 The Rev. Levi Lawrence left to Eglwys Adulam, Merthyr Tudful.
1851 25 members with Parch John Taihirion Davies as Minister.
1869 71 members and the chapel was now too small. It was decided to build a new chapel.
1870 July 3rd and 4th. The present chapel was opened at a cost of £830.00.
1878 Membership was 144. By ythe end of the year 27 members were lost because of the closure of a coal mine in the locality. Members moved to the Rhondda and Cwm Garw.
1898 The Vestry and stable were built for £250.00
1901 September. A Jubilee Meeting was held to celebrate 50 years of the ministry of John Taihirion Davies.
1904 Parch. John Taihirion Davies died.
MINISTERS - GWEINIDOGION
Y Parchedig Lemuel Smith 1841 - 1842
Y Parchedig Levi Lawrence 1842 - 1847
Y Parchedig John Taihirion Davies 1851 - 1904
