Why are England rugby fans getting behind Wales?
The number of high-profile English rugby fans throwing their support behind the Welsh team before their crunch semi-final showdown on Saturday is the latest unexpected turn-up, in a Rugby World Cup full of surprises.
Welsh rugby fans who were backing Australia when England pipped them to the cup in 2003 might be among those most wrong-footed by the trend.
But an expert in Anglo-Welsh sporting relations is refusing to be taken aback by the apparent reversal of decades of banter and rivalry between the two neighbouring nations.
Dr Martin Johnes, a lecturer in Welsh history at Swansea University, says it reveals nothing new about the English that they can switch their allegiance to a team like Wales in the absence of their own team.
He says a genuine feel for the underdog - and a fellow British team to boot - lies behind the phenomenon.
Those looking for evidence of a seismic shift in attitudes on either side of Offa's Dyke, suggests Dr Johnes, should wait for the day when Welsh rugby fans decide to return the favour.
England began to turn red on Sunday, the day after Martin Johnson's team was beaten by Wales' opponents this weekend, France.
A London-based newspaper ended its editorial with the words: "We are all Welsh now".
Chris Evans stoked the fires further on his BBC Radio 2 breakfast show, which is celebrating all things Welsh this week.
"Come on Wales," wrote Evans in his BBC blog this week. "Peace and Love and Lots Of Leeks".
Berkshire-born entrepreneur Peter Jones, of the BBC's Dragons Den programme, has also taken to the internet to pledge his support for Warren Gatland's men.
He tweeted: "England out. France deserved to win. Now need to check ancestry. I'm sure with my surname there must be a bit of welsh there. Come on Wales!"
And he has been joined by no fewer than three former England rugby internationals.
Will Greenwood, a member of England's 2003 cup-winning team, tweeted: "Off to buy my Wales top on way to NZ".
His former team-mate Austin Healey added: "just jumping on their band wagon they could win this".
Even ex-England captain Will Carling told his followers: "Think Wales look awesome. Tight 5 strong, back row great. So got to fancy the boys in Red".
It is true that both Jones and Evans are good Welsh surnames, and Carling did once serve with the Royal Regiment of Wales. But something is wrong here, surely?
"There hasn't been any great shift in English attitudes to Wales," insisted Dr Johnes, author of a history of Welsh sport. "It's a combination of following the underdog and a fellow British team.
"It's no different to them supporting (Scottish tennis player) Andy Murray."
However if the boot were on the other foot, with England taking on a non-British team in the semi-final, inclinations in Wales towards the men in white would be quite different, said Dr Johnes.
"If it was the other way round I don't think we would see the same attitude," he said.
"In rugby the English rugby team is seen very much as the establishment. Attitudes will be similar to those attitudes about class.
"The English rugby team represents a view of Englishness that is arrogant."
Welsh soccer fans will happily support England's soccer team, contests Dr Johnes.
"In rugby it doesn't work like that," he added. "Wales considers itself as the equal in rugby but not in football.
"It's easier for English rugby fans because there aren't the same negative connotations. Wales is in world sporting terms a small nation and people like the underdog to do well."
Welsh journalist Carolyn Hitt feels England's fans have been attracted to the Welsh team, and repelled from their own, by each team's contrasting behaviour on and off the field in New Zealand.
"Wales have had their drinks embargo and choir practice while England have had their dwarf-tossing and blondes," says Ms Hitt. "Maybe they are responding to that.
"I don't think they normally wish they were like us but maybe this time they do."
Ms Hitt points to the attractive rugby played by Wales, and the feelgood factor around the Welsh camp.
"They've been confident without being arrogant," she said. "I think people have responded to that, especially when their own team has let them down.
"There's something nice about it. I love the rivalry and tribalism of rugby but not when it's taken too far."