More than 5000 Joneses are listed in the White Pages - bloodlines the Auckland Welsh Club hopes will translate to support for Wales in their Rugby World Cup clash with France.
Ireland's and Scotland's support during the tournament has been swelled significantly by New Zealanders who embraced their Celtic heritage.
But Auckland Welsh Club president Barrie-John Partridge said that had not been the case for Wales, despite their great form.
"It seems as though everyone claims to be Irish if someone 12 generations ago visited Ireland.
"But with the Welsh it's a bit different, it's generally only those of us who have had Welsh parents or grandparents."
Part of the problem is that people born in Wales are only a small proportion of all British immigrants who came to New Zealand.
Those of Welsh descent also often married people of other origins, which meant it has been difficult for the Welsh to maintain a distinctive identity in New Zealand.
"Welsh tend not to travel as much as other Celts, although there have been a couple of great Welsh migrations," Mr Partridge said.
"We established the Patagonia colony in Argentina, so that's the only other Welsh-speaking region of the world. And we went to the Americas as well."
Mr Partridge, who moved to New Zealand with his parents at 5 from Gilfach Goch in South Wales, said he hoped support would now swing behind the Welsh.
"There hasn't been the New Zealanders adopting us like they have the Irish. But I think we will have a lot of Irish and New Zealanders supporting Wales now.
"For one, Kiwis think they can beat the Welsh quite easily so they want to play us in the final. But they'll be in for a hell of a shock if they do think that."
Mr Partridge and other members of the 150-member club had attended all the Welsh team's World Cup matches.
He encouraged those named Jones, Williams, Evans and likewise to don red and get behind what could be a historic World Cup campaign.
"I do think there will be a massive surge in support, especially for this game on Saturday. There'll be a sea of red."