"Jones" is considered a quintessentially Welsh name, but author Rocet Arwel Jones says that it's not Welsh at all.
"If Wales had a surname, it would be Jones," writes Mr Jones in his Welsh-language book.Jones says that the surname in Wales is an anglicized version of the truly Welsh patronymics "ap John" or "ap Siôn," and appeared only after the English system of using surnames took hold in Wales.
"And yet it's a surname that starts with a letter that's not even in the Welsh alphabet. Does that make it an English surname?
"It was a surname in England before such a thing as a surname existed in Wales at all."
"The first Jones surname appears in Huntingdonshire, in England, in 1279. Looking at the collection of wills in the National Library [of Wales], the first Jones to appear there is Roger Jones from Tregynon who died in 1564." [Link]