The meeting between Her Majesty and Mr McGuinness had been hailed as a deeply symbolic gesture, and a sign of the political advances in Northern Ireland over the last ten years.
But instead, all the talk afterwards was about the overt sexual chemistry between the pair.
The BBC's Ireland correspondent Mark Simpson said: “When they clapped eyes on each other, it was like a cruise-liner full of fireworks going off at once.
“And then the handshake........well let's just say it was all they could do not to go and book a room at Premier Inn on the spot.”
At an evening reception in Stormont, the Queen was seen twirling her hair and making furtive glances towards Mr McGuinness.
At around 9pm, she retired to her private quarters, complaining of an upset chin.
Fifteen minutes later, Mr McGuinness made his excuses, distractedly telling a colleague that he had to “water his desk”.
Neither of them were seen until breakfast the following morning, when, according to sources close to the grapefruit juice, the Queen appeared flushed and Mr McGuinness “had a grin the size of Belfast”.
A Buckingham Palace spokeswoman denied there was any romantic relationship between Her Majesty and Northern Ireland's Deputy First Minister.
The spokeswoman said: “They are merely good friends.
“Very, very good friends,” she added with a naughty laugh.