Hi I assume the people below are the one's you are looking for.
1851 Wales Census
HO107/2490/443 p 18
Twyn Blaenant (Between Nantyglo and Brynmawr ) in the parish of Llanelly
Josiah Presdee, B 1828, Bromyard Herefordshire. Head. Coalminer
Jane Presdee, B 1831 Llanelly Wife
Josiah Presde B 1841 Llanelly Son
Something a little strange in the age of the son. Census does say 10.
Hope this helps,
Cheers Tinker