Image copyright PA Image caption Sinn Féin's Martin McGuinness shook hands with the Queen for the first time when she visited Belfast's Lyric Theatre in June 2012

Martin McGuinness will attend a banquet hosted by the Queen during next week's state visit to Britain by Irish President Michael D Higgins.

Sinn Féin president Gerry Adams said the decision had to be viewed against the backdrop of huge political change in recent years.

President Higgins will be joined by his wife, Sabina, and the Irish prime minister, Enda Kenny.

The visit, the first by an Irish head of state, begins on 8 April.

'Unthinkable'

Martin McGuinness, who is Northern Ireland's deputy first minister and a former IRA commander, refused to sit in the House of Commons - when he was an MP - because he would have had to swear an oath of allegiance to the monarch.

He shook hands with the Queen, both in private and in public, during her visit to Northern Ireland in 2012.

Media playback is unsupported on your device Media caption Enda Kenny: "It should be possible for members of the Royal Family to visit Dublin during the centenary commemoration ceremonies"

The handshake was regarded as a symbolic moment for the Northern Ireland peace process.

It was seen by many as one of the most significant of her reign as the IRA paramilitary group murdered the Queen's cousin, Lord Mountbatten, while he was on holiday in the Republic of Ireland in 1979.

The state banquet is to be staged at Windsor Castle, in honour of President Higgins.

During his UK visit, he will address both Houses of Parliament, another first for an Irish head of state.

Mr Higgins will also visit the Royal Shakespeare Company in Stratford-upon-Avon and attend another major dinner at the Guildhall in the City of London, given by the Lord Mayor.

Analysis As a youth, Martin McGuinness wore the uniform of an IRA volunteer - secretly, illegally and defiantly. Now, decades later, he will don a white tie and tails and publicly, cheerfully and - perhaps -still defiantly, attend the Queen's banquet at Windsor Castle. We should not be too surprised. His journey has already seen him shake the hand of the Queen. Not to attend the first state visit of an Irish president would undermine all his promises, made as an Irish presidential candidate, that he would work for peace. It will put him in the company of Ireland's most senior figure, Michael D Higgins, and the presidency is a post that Sinn Féin covets. It will also win praise in Dublin and the Republic, helping to reverse the political blunder of Sinn Féin's refusal to attend the Queen's visit to the Irish presidential residence in 2011. And whatever votes Sinn Féin loses in Northern Ireland, if any, will be offset by potential gains in the south of Ireland. Having conquered Northern Ireland, it is to the south that Sinn Féin's hungry eyes look for growth. This decision is good for Martin McGuinness, peace and for Sinn Féin.

During the visit, the Queen will host a reception for leading figures from Northern Ireland's cultural, political and business life.

Irish Prime Minister Enda Kenny said the president's first UK state visit would mean "an enormous amount to the people of Ireland, but also to the people of Britain".

"Symbolically, it's of enormous importance, but also practically, in that it brings the relationship between the two countries and the two peoples to an unprecedented level.

"This was unthinkable 20 years ago," he told the BBC's Andrew Marr Show.

'Move on'

Regarding the Sinn Féin representative's appearance at the Queen's state banquet, Mr Kenny said: "Martin McGuinness, as deputy first minister in the assembly in Northern Ireland has been very forthright and very pragmatic in what he has been doing here.

"I don't see why he shouldn't attend, of course. This is all part of the building of relationships between the two countries and peoples on both sides of the divide.

"We've got to move on and not be blocked by the past," the Irish prime minister added.

The visit by President Higgins follows on from the Queen's historic state visit to the Republic of Ireland in May 2011.

During her first ever trip to the Republic, the Queen laid wreaths in tribute to Irishmen who died fighting for Britain in both world wars and also for Irish rebels who died fighting for independence from British rule.

In a visit rich in symbolism, the monarch also spoke a few words in the Irish language as she addressed a state dinner in Dublin Castle, the building that had once been the seat of British rule in Ireland.