My John Llewellyn (b. 1836) lived with his siblings and parents on Bute St. in Aberdare in the 1851 census (HO 107/2460, bottom of pg. 13). I have seven children born to this John and Margaret Ann Williams. John is my g-g-gf. Was your Thomas (John's older brother) born in 1832? Your Thomas and my John may have been brothers. Let me know.