The Queen's historic visit to the Republic of Ireland was a "game-changer" that heralded a new era in Anglo-Irish relations, David Cameron has said.
In a documentary, The Queen's Speech, to be shown tonight on Irish state broadcaster RTE, the prime minister said the "strong relationship" between London and Dublin brought about as a result of the peace process had been bolstered further by the tour.
The Queen became the first British monarch to travel to the Republic in 100 years in May. The two-day visit sparked an unprecedented security operation that cost £26.2 million and included land, air and sea patrols and a ring of steel around the centre of the Irish capital.
Sinn Fein's Gerry Adams said at the time the tour was "premature" but it was marred by only minor protests.
Mr Cameron told RTE: "It's been a game-changer, to use that terrible modern expression.
"What was already a strong relationship, and what was already becoming warmer and more positive because of the settling down of the Northern Irish issue, I think her visit has just put that into a massive new perspective.
"She just warmed the hearts of people, and so this true relationship - that I think had been going on between British people and Irish people for years - has really now been able to flower."