Hope you had a good round of golf Hugo what a lovely day for it.
You have mentioned your Father's Mum died while he was young & I have found 2 possibles both Ellen Maria Hughes born 1879, 1 died in 1935 & 1 in 1926 registered in Conway, was she either of these? The family by the Afon Gyffin could have been your Taid Evan's sister Margaret Ann she married Elias Eardley & they lived in Bronant, which is along the Woodlands on the way to Gyffin & overlooks the river. By the way her Will is in the Archive if you want a look CD4/8295+296 dated 7/1/1927 + 11/12/1927.
The Marriage information I have is a copy of the register for Joseph & Jane. It was 21/11/1863 in the Parish Church Penmachno. Joseph was full age, a Stonemason, Father Hugh Hughes Stonemason, no address just Penmachno. Jane was 19, Father Evan Hughes Quarryman & again just Penmachno.
I found Jane & her parents living at Cwm Lane on the 1851 Census, so could that be the house your father talked about if it was still in the family? Her parents are Evan Hughes born 1811 Penmachno, died 6/6/1874 Penmachno & Grace Davies born 1814 Penmachno, died 1/1/1884 Penmachno. They married 8/8/1835 Penmachno