A multi-national grassroots movement is calling for a new agreement to permit free travel, trade and policy co-ordination between Canada, Australia, New Zealand and the United Kingdom.

CANZUK International says such an agreement would build on the pre-existing socio-economic bonds that the four countries have in common, while strengthening trade, military and diplomatic relations among the proposed member nations.

A petition launched by the organization three years ago has racked up more than 200,000 signatures online.

“This idea is definitely a vote winner,” John Bender, chairman of CANZUK International, told CTV’s Your Morning from London on Wednesday.

Bender says a CANZUK agreement would be an easy fit for Canada, New Zealand, Australia and the U.K., because there are already a number of cultural similarities between the four countries.

“Canada’s head of state is shared by 15 other countries, there are profound cultural links, there are historical links (and) a common legal tradition,” he said. He added that all four nations also have close security ties through the Five Eyes intelligence-sharing program, which includes the United States as well.

He says a CANZUK agreement would improve upon that positive relationship by allowing free trade and migration among the four countries.

However, he says there would still be security measures in place to restrict individuals who are deemed a threat to national security. “It wouldn’t be out-and-out unfettered migration,” he said.

Bender, who is based in the U.K., says he’s already spoken to British Prime Minister Theresa May and Foreign Minister Boris Johnson about a CANZUK agreement. “They are very keen on the idea,” although they’re a bit “preoccupied” with Brexit at the moment, he said.

Although the idea sounds exciting at first blush, it would also raise a number of social service-related issues that would need to be ironed out. For instance, what if a Canadian chooses to retire in New Zealand? Who pays employment insurance to a laid-off Australian living in Canada? And what health coverage will a Canadian be afforded in the U.K.?

Bender did not directly address those issues when asked about them on Your Morning.

“Those concerns are less held by the man in the street, by the grassroots constituency,” he said.

The organization was founded in January 2015.