The answer is simple, he was named Jones since this is the English version of the Welsh Siôn. William's mother was Elizabeth Rowland who was from Llanddeusant, a village in the Brecon Beacon hills about 9 km due south of Llandovery. William was born on a farm on the island of Anglesey and the family moved to Llanbabo on Anglesey, then moved again after the death of William's father.
Ang sagot ay simple, siya ay pinangalanang Jones dahil ito ay ang Ingles na bersyon ng Welsh Sion. William's ina ay Rowland Elizabeth na noon ay mula sa Llanddeusant, isang baryo sa Brecon Beacon Hills tungkol sa 9 km dahil sa timog ng Llandovery. William ay ipinanganak sa isang sakahan sa isla ng Anglesey at ang pamilya inilipat sa Llanbabo sa Anglesey, pagkatapos ay lumipat muli pagkatapos ng kamatayan ng William's ama.