People often wonder why so many Welsh surnames are essentially English Christian names: Richards, Barry, Lewis, Davies (a corruption of David), Evans, Thomas, Hughes and many more.
In the early medieval period, the Welsh didn’t have surnames at all. Rather as continues to exist in Iceland today, people were known as “the son of” or “the daughter of” their father’s name, using a little word “ap” or “ferch” for women.
So if your name was Tomos, your sister Arianwen, and your father was Huw, you would be Tomos ap Huw, and your sister would be Arianwen ferch Huw.
If there were two Tomos ap Huws in your village, you would then further refer to your grandfather, who might have been called Iolo. You would then be Tomos ap Huw ap Iolo. Where further identification were needed, you could then take it still further back to your great-grandfather, and so on, building up an immense genealogy.
It’s hell when you’re trying to research Welsh medieval princes – they’re all called the same! Whatever you do, don’t confuse Gruffudd ap Llewelyn with Gruffudd ap Llewelyn Fawr – totally different people!
As you’ve probably realised already, it’s also totally inadequate for record keeping. By the sixteenth century, all Welsh were required to adopt English-style surnames, at least for the purpose of public administration. Most simply continued using their father’s name, as they always had. So Tomos ap Huw was rendered “Thomas Hugh’s son,” which became “Hughes.” Or “ap Iestyn” could be rendered “Stephen’s son”, later morphing into Stephenson. Where a name had no direct English equivalent, it was rendered phonetically; so Gruffudd became Griffiths.
So where did Jones come from? Ioan was as common a name in Wales as John in England. Most of those whose father was Ioan were recorded as “John’s son” or Johns. This has evolved into Jones.