Queen in historic hand shake with Sinn Fein
McGuinness is now the Deputy First Minister for Northern Ireland. The Queen has never met a senior figure in the now-defunct IRA or its political wing, Sinn Fein.
McGuinness, an ex-IRA leader, was the chief negotiator for Sinn Fein during talks to end IRA`s violence in Northern Ireland.
The meeting between the two took place at the Lyric Theatre in Belfast during an event organised by a charity organisation, Co-Operation Ireland, which works to bring communities together. They shook hands at a private meeting and later shook hands in public.
The prime minister`s official spokesman said the Queen`s visit to the Republic of Ireland last year had "taken relations between the two countries to a new level".
The spokesperson added: "We think it is right that the Queen should meet representatives from all parts of the community." Last year, McGuinness had refused an invitation to meet the Queen during her visit to Northern Ireland.
Today`s meeting between the two was seen as difficult for republicans in Northern Ireland who view the Queen as the representative of an occupying country. The meeting and the hand shake are seen as a major milestone in efforts to normalise relations between nationalists and unionists in Northern Ireland.