In a statement this afternoon, the North's deputy First Minister, Sinn Féin's Martin McGuinness said:
"As you know, I will be attending events as part of the State visit of Úachtarán na hÉireann to Britain.
"I will be doing so as a representative of all of the people of the North, and in the context of conflict resolution and of building reconciliation among the people of Ireland, and between the people of Ireland and the people of Britain.
"I am conscious that this decision is significant and involves political and symbolic challenges for Irish republicans.
"However, my presence alongside Peter Robinson brings an all-island dimension to this historic event which, it is worth noting, has taken all of 93 years to happen.
"As the record of the Peace Process demonstrates Irish republicans have always been prepared to take decisions and risks for peace and reconciliation.
"I am an Irish republican. A united Ireland has been, and continues to be, the primary objective of my political life. I want to see an end to Partition and unity of the Irish people through a genuine process of reconciliation based on equality and tolerance.
"I want an Ireland in which one can be British or Irish and live in harmony and mutual respect with their neighbours. There is now a peaceful and democratic way to achieve this.
"There have been huge and positive political changes in recent years. There is now a clear process of transition ongoing within the island of Ireland and between Ireland, including the North, and Britain.
"I firmly believe that my attendance marks another significant step. It is not an end to the process of building a new relationship based upon equality but is important part of that journey."