I've now been through the records of the Gyffylliog/Cyffylliog Cavenistic Methodist Chapel. These were produced, among others, by Clwyd FHS. I've also checked the records of other chapel records in the area.
This is what I have for children baptised at Cyffylliog Calvanistic Methodist Chapel with parents Thomas Williams and Anne (mn Jones):
Elizabeth Williams, born 15th Nov and bpt 11th Dec 1812/of Bont. Daughter of Thomas Williams, lab. and Anne, mn Jones
Mother before marriage - Denbigh, Father before marriage - Llanynys
Thomas Williams, born 16th and bpt 23rd of December 1814/of Bont. Son of Thomas Williams, lab. and Anne, mn Jones
Mother before marriage - Denbigh, Father before marriage - Llanynys
Cathrine Williams, born 20th and bpt 29th March 1818 of Bontuchel. Daughter of Thomas Williams, lab. and Anne, mn Jones
Mother before marriage - Denbigh, Father before marriage - Llanynys
John Williams, born 16th and bpt 27th Nov 1820 of Bron Mary. Son of Thomas Williams, lab. and Anne, mn Jones
Mother before marriage - Denbigh, Father before marriage - Llanynys
Joseph Williams, born 4th and bpt 17th August 1823. Son of Thomas Williams, lab. and Anne, mn Jones
Mother before marriage - Denbigh, Father before marriage - Llanynys
(there was an Ebenezer Williams bpt there but parents were Moses Williams and Anne Lloyd)
Note - no Benjamin and I think parents were married before 1814. Also residence of parents were different than previously stated.
None of the other chapel records that I've looked at have a Benjamin Williams to parents with the names mentioned.
John - could you give me the source of your informtion about the baptism, please.
Gadget