Mr Carney arrived in Dublin yesterday and will spend today in Mayo, his ancestral home.

His paternal grandparents, Robert Carney and Nora Moran, were from Aughagower in Co Mayo but emigrated to Canada on the steamship Montnairn in July 1925 and married in Canada a century ago, in April 1926.

The Carneys and the Morans were tenant farmers on the estate of Lord Sligo, according to research by the Westport Historical Society.

“Robert and Nora were raised during an era of great upheaval and transformation in Ireland.

“Their families had lived through the aftermath of the Great Famine and witnessed waves of mass emigration,” research from the Westport Historical Society said.

Mr Martin said Mr Carney’s grandparents, who were born in Aughagower, would be “enormously proud” that their “sacrifices and hardships paved the way for his remarkable accomplishments and achievements”.

At an event at Dublin Castle on Saturday, the Taoiseach suggested that the prime minister’s historical ties to Ireland stretch back even further.

He said that after visiting the Book of Kells in Trinity College, the two men saw a page in the Book of Armagh that linked Aughagower to the country’s patron saint.

Mr Martin said: “The page opened for Tírechán’s account of St Patrick’s journey through Mayo and he visits – you won’t believe it – Aughagower before going to Croagh Patrick.”

He added: “In that paragraph, Patrick consecrates a church in that place, Aughagower, with the maiden Mathona, who’s clearly setting up, we think, a nunnery there.

“And Patrick said to the people gathered ‘there will be good bishops here, and from their seed, blessed people will come forth forever in this sea’.”

Mr Martin went on to joke: “I knew he was a visionary, but I never quite knew that St Patrick was that visionary – and he clearly had Mark Carney in mind.”

The Taoiseach also referenced the “extraordinary journey” of Mr Carney’s grandparents in search of a better life across the Atlantic.

“They could scarcely have imagined that one day their grandson would return to Ireland as Prime Minister of Canada, welcomed by the people of the country they left behind.”

He told Mr Carney that when he walks the roads his grandparents walked in Mayo, he would discover that “Ireland never forgets her own”.

Referencing the poem Thresholds by Irish poet John O’Donohue, Mr Carney told the same event: “My grandparents crossed their threshold in Mayo a century ago – into a life of a country that was still building itself, as Canada always has.

“And they were part of four and a half million Canadians who are the product of similar decisions.”

He added: “Today, half a million people who travel between our countries every year cross thresholds.

“Now, there’s one other threshold that I’ll mention at which Canada, Ireland, Europe now stand – and that’s the rupture in the global system.

“From rules-based to arms-based, from right to might, from values to vanquished.

“Where will we go, and to what purpose? And I’d suggest that the thresholds that we have crossed and those before us have crossed, the shared values that have been forged in doing so, will bring us forward.”

On Saturday, the two leaders announced a new “bilateral co-operation framework” on trade and investment, life sciences, research and innovation, and security and defence.