The Queen's visit to Ireland will "put a seal on the past and build for the future", former British PM Sir John Major has said.
Sir John, who first set in train the peace process in Northern Ireland which led to the current power-sharing arrangements, said the visit is the most significant royal trip for many decades.
He dismissed the suggestion of Sinn Fein leader Gerry Adams that the visit is "premature" and said he did not anticipate that the Queen will deliver any apology for the UK's past involvement in Ireland.
Speaking to BBC2's Newsnight, Sir John said: "This (visit) puts the seal on a relationship that was sour and is no longer sour. It puts a seal on the past and builds for the future. I can't think of anything of equivalent significance in the last few decades."
And he added: "I think it will set a new mark for relations between the UK and Ireland."
Sir John said the atmosphere of relations between London and Dublin had "changed beyond belief" over the past 20 years.
From a position in the early 1990s when the rare conversations between prime ministers of the two countries were "frosty", UK-Irish relations have now reached the point where they are close political allies and major trading partners with 200 flights a day between their airports and a high level of "interplay" between their populations, he said.
"The atmosphere has changed tremendously and I think the Queen's visit will be not reflecting on the past, but looking forward to an ongoing relationship," said Sir John.
Asked if Her Majesty should make any apologies during her visit, he replied: "I don't think the Queen is going there to look at the past at all and I don't anticipate that that will be the case.
"I think what the Queen is going there for is to do what she has consistently done since she became Queen, which is to look to the future."