On Saturday evening, party leader Gerry Adams released a statement confirming that the Stormont deputy First Minister will visit Windsor Castle and attend other official events in London during the historic official visit by Irish President Michael D Higgins.The four-day state visit, which officially begins on Tuesday, marks the first time an Irish head of state has been formally invited to the UK by a British sovereign.Speaking in Derry on Sunday, Mr McGuinness, a former MP who refused to take his seat at Westminster, said he had accepted the invitation to send a "message to everybody about how things have changed"."If we could find all sorts of reasons why we should not accept an invitation from Queen Elizabeth to go to her house ... [then there's] no doubt she has any number of reasons as to why she should not invite us to her house," he said.Mr McGuinness said that he felt both governments had been "rather sluggish over the course of recent times [and] would do well to learn the lessons of what is happening here in the course of next week."He added: "They have a huge responsibility to play and unfortunately, they haven't been playing it in the course of the last number of months."There is a long-standing practice of not commenting on individual invitations. That said, Her Majesty is greatly looking forward to this historic state visit and welcoming all guests to Windsor Castle.Buckingham PalaceEarlier, Taoiseach Enda Kenny welcomed Sinn Féin's decision to send a representative to attend an event during the official state visit.The Fine Gael leader said that people had to "move on and not be blocked by the past".Mr Kenny, speaking to the BBC's Andrew Marr, said he "didn't see why [McGuinness] shouldn't attend".He said: "This is all part of the building of relationships between the two countries and peoples on both side of a divide."He's an elected member of the executive services, Deputy First Minister - we've got to move on and not be blocked by the past."President Higgins and his wife Sabina were issued the invitation to stay at Windsor Castle by the Monarch last year.The ground-breaking visit follows the Queen's historic trip to Ireland in May 2011.At the time, Mr McGuinness had snubbed the gala banquet held in her honour at Dublin Castle.CHAR(13) + CHAR(10)Over a year later, the Queen and Mr McGuinness made history when they met and shook hands in Belfast's Lyric Theatre.Mr Kenny said: "The Queen herself spoke in Dublin Castle, which was the symbolic head of the British Empire in this country for several hundred years."She said if you looked at history, there were some things you might do differently and some things you might not do at all, and her contribution in Dublin three years ago closed a circle of history."Meanwhile, Mr Adams admitted that while the announcement "may not be welcome by opponents of change, it is yet another example of Sinn Fein's commitment to an inclusive future based on tolerance and equality.""This decision may cause difficulty for some Irish republicans in light of ongoing difficulties in the north but I would appeal to them to view this positively in the context of republican and democratic objectives and the interests of unity and peace on this island."Mr Adams said the state visit by the Irish president needed to be viewed against the backdrop of huge political changes over recent years.A Buckingham Palace spokesman said the Queen was looking forward to welcoming all guests to Windsor Castle.