History was instantly made when Martin McGuinness and the Queen first shook hands in 2012.
Almost 15 years had passed since the Good Friday Agreement brought a formal end to the Troubles.
Yet the pleasantries between the former IRA commander - who has died at the age of 66 - and the symbolic head of the British armed forces still marked an iconic moment in the move towards lasting peace in Northern Ireland.
The meeting at a charity event in Belfast was charged with personal significance too.
The Queen had lost her cousin, Louis Mountbatten, to an IRA bomb in 1979 at point when Mr McGuinness was the group's chief of staff.
The pair discussed the killing as they met behind closed doors in a room within Belfast's Lyric Theatre during an event celebrating the arts in the Republic and Northern Ireland.
Mr McGuinness held the monarch's hands for a few moments, spoke to her in Irish and told her the words meant: "Goodbye and God's speed."
Hours later the smiling deputy first leader described the meeting as "very nice" but joked: "I'm still a Republican."
A day later he recognised its "momentous and historical" significance, saying it 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".
"It is an offer I hope many will accept in the same spirit it was offered," he said.
The meeting was quickly hailed around the world.
Former US secretary of state Hillary Clinton described it as "the most remarkable sign of change yet" in the peace process.
Even more surprising was the warmth with which Mr McGuinness would go on to openly show when speaking about the head of a British establishment he had once so reviled.
"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," he told a BBC documentary.
PA photographer Paul Faith, who captured the famous first meeting in 2012, said the significance of the shot "didn't really sink in" until he went to the newstands the next day.
"Every front page was carrying the photograph and it hit me that this was going to be a historic image," he said.
Recalling the meeting, he said: "I remember that Martin appeared very relaxed and confident and happy to stand beside the Queen."
The meeting became one of several handshakes recorded on camera.
The pair met again as recently as January, when Mr McGuinness was heard inquiring about the Queen's health after she fell ill over the festive period.
The Queen replied: "Well, I'm still alive".