The conflict between their supporters had lasted centuries but the hugely symbolic handshake between the former commander of the IRA and the head of the State he so despised took just 3.7 seconds to execute.
It was a dramatic scene that the creative team at the Lyric Theatre in Belfast would have rejected as too outlandish a storyline had someone written a play speculating that it would take place.
And just minutes later Martin McGuinness, whose aides had said he wouldn’t be talking about his historic two-hander with the Queen, briefly stopped to talk to me outside the Lyric.
Its patron is Liam Neeson, who once famously played the part of Michael Collins who, like the deputy First Minister, is seen by some Republicans as a traitor.
I asked how the meeting had gone. He replied: “It went very well.” When I inquired if he had lost any convictions he responded: “I am still a Republican.”
Another asked what it had been like to meet the Queen. He said: “Very nice.”
History will never tell us what the Queen thought of her tete-a-tete with a terrorist of old. But the second of her two handshakes with Mr McGuinness lasted three times longer than any of the others with the rest of the VIPs in the farewell line-up at the Lyric.
The only member of the public to witness the handshake for real was a woman who took advantage of the fact that her son lives on the other side of Ridgeway Street from the Lyric to see the Queen.
The woman, who would only give her first name – Lorraine – never imagined she would witness the most publicised handshake in decades.
“It was the Queen I came to see. I am a big fan of hers. I think she is brilliant. As for the handshake, I was married to a policeman and I just take things as they come and get on with life.”
The first handshake took place away from prying eyes and out of sight of the one photographer, one reporter and one TV camera crew allowed into the theatre.
The Queen, Prince Philip, Irish President Michael D Higgins and his wife Sabina, Martin McGuinness and Peter Robinson were shepherded, along with their advisers, into the Lyric’s McGrath suite — named after theatre benefactor and Prudential insurance chairman Harvey McGrath.
The curtains on the windows were drawn for the five-minute meeting at which Mr McGuinness spoke not only of the significance of the Queen’s current visit but also of the lasting impact of her words and gestures in the Republic last year when she talked about the pain of all victims and about the need for building on the peace process.
Afterwards, she went into the Lyric’s cafe bar to see paintings by local artist Colin Davidson of actors, poets and playwrights from Northern Ireland.
But the Duke of Edinburgh wasn’t laughing after Martin McGuinness tried to engage him in conversation. The Prince, whose uncle Lord Mountbatten was killed by the IRA in 1979 when Mr McGuinness was a prominent figure in the Provisionals, looked decidedly uncomfortable and moved away quickly. “He leapt out of the way like a scalded cat,” said one observer.
It was a fleeting moment but it perhaps said more about the Royal couple’s feelings about the meeting than anything they would be able to say for themselves.
But as the Prince was departing from the Lyric he too readily exchanged a handshake with Mr McGuinness, who had welcomed the Royal visitor in Irish and bade her farewell with another phrase, translated as ‘Goodbye and God speed’.
He did not wish her a speedy return.
After the curtain came down on one of the most remarkable productions at the Lyric, officials turned down requests for journalists and photographers to see the room where the private handshake took place.
Sources admitted that a picture of the McGrath Suite, which is usually used for creative learning classes, is readily available on the internet.
But it had been a day of strange decisions, mostly at the behest of Buckingham Palace and security advisers. Negotiations about the arrangements for the public handshake went on long into the night.
Even at the height of The Troubles the press were invariably permitted to film the Royals as they arrived at their locations.
But this time the media — apart from the ones ‘pooling’ their pictures for other outlets — were ordered to observe what was effectively an exclusion zone all around the Lyric and the Stranmillis area and security was very tight, with marksmen on the roof.
Even loyalists, who had bedecked their homes in nearby Annadale Flats with Diamond Jubilee flags, had to stay back.
Belfast’s former Lord Mayor Billy Bell was among the well-wishers who had to peer through the foliage of trees for a quick and distant look at the Royal party.
“It’s daft,” said Mr Bell, who received an MBE from the Queen.
David Livingstone, who had travelled from his home near Shaw’s Bridge to get a picture of the Queen, was told in no uncertain terms by police that he couldn’t cross the Governor’s Bridge to the Lyric.
“What harm would we be doing?” he asked “It must be because of this handshake. I don’t think the Queen should be shaking Mr McGuinness’s hand but, at the end of the day, this is life.
“And if you look all over the world in her 60 years on the throne she has shaken hands with many people who were terrorists and ended up running their countries. We’re no different.”
May Davis (79), who lives in the Flats and who wore a red, white and blue poncho, was furious that her ‘one-off’ chance to see the Queen was blocked by police.
Back at the Lyric, officials were hoping history would be replaced by hysterics yesterday afternoon as the matinee audience for the Oscar Wilde comedy The Importance of Being Earnest started to arrive not long after the Queen departed.
Inevitably the thoughts turned to plays which the Lyric might stage in the future to reflect an important day in their development.
The Queen And The Rebels by Ugo Betti; Arms And The Man by George Bernard Shaw and The Shadow Of A Gunman by Sean O’Casey were instantly rejected.