Clare on Family Tree Circles

My great grandmother was a Margaret Jenkins born in Newport Mon in about 1855/6. In April 1874 she married a John Miller also from Newport, Mon and on the Marriage Certificate is states that her father was a William Miller, forman in a steel works.
I haven't yet been able to find her birth and need to find her family who might have moved to Cardiff, S.Glam.
In the 1871 census I think I have found her in Cowbridge Road, Canton,Cardiff as a Domestic Servant, aged 15 but I have been unable to find her on the 1861 census aged 5 so am unable to find out the name of her mother.

I am looking for Ancestors of William Newton born in Wishford, Nr. Salisbury in 1852/3. He was a carpenter and for a time worked at Salisbury Cathedral.
He married Sarah Selina Conduit in March 1876 in the Parish Church in Woodford,Wilts.
Her parents were John Conduit(1812) and Emma Fruen(1813)