The Queen is to send a private message to the widow of Martin McGuinness following his death aged 66.
Former IRA leader Mr McGuinness was one of the most controversial figures in Anglo-Irish history before helping to pave the way for peace in Northern Ireland years later.
He met and shook hands with Queen Elizabeth at a charity event in Belfast in June 2012 in a landmark moment which would have once been unimaginable.
On Tuesday, following the announcement of Mr McGuinness’ death after a short illness, Buckingham Palace indicated the Queen would be contacting his wife, Bernie.
Mr McGuinness was 21 and second-in-command of the IRA on Bloody Sunday in 1972, when 14 civil rights protesters were killed in Derry by soldiers.
It is remembered as one of the bloodiest and most notorious events during The Troubles as the conflict between loyalist Protestants and republican Catholics came to a head.
Years later, Mr McGuinness worked at the centre of the peace process which led to the historic 1998 Good Friday Agreement.
Ex-Prime Minister Tony Blair said the peace agreement would not have been possible without Mr McGuinness’ “leadership and courage”.
He added: “Once he became the peace maker he became it wholeheartedly”.
Martin McGuinness - In pictures
Following his handshake with the Queen five years ago, Mr McGuinness said their meeting had the potential to define "a new relationship between Britain and Ireland and between the Irish people themselves".
In a speech in Westminster he said the handshake "was in a very pointed, deliberate and symbolic way offering the hand of friendship to unionists through the person of Queen Elizabeth for which many unionists have a deep affinity".
Years later Mr McGuinness paid tribute to the Queen for meeting him and said: “I liked her courage in agreeing to meet with me, I liked the engagements that I've had with her.
“There's nothing I have seen in my engagements with her that this is someone I should dislike - I like her.”
