The forename Johannes was
borrowed in the Roman period and became Ieuan in Welsh. This is
pronounced something like Y-eye-an. When permanent surnames were adopted
in Wales, Ieuan sometimes became Jones and sometimes Evans.
A document of 1533 names Thomas ap Ieuan ap David ap Blethyn alias Thomas
Jones. In the mediaeval period, John was borrowed and in time this
became used as a surname, sometimes unchanged, sometimes in the style Jones.
The forename John is known to have been used in Wales in the thirteenth