Her words, in a family not known for their gushing sentiments in public, were remarkable. Photo / Getty Images
She spoke as monarch, host and, most importantly, mother. And in some of her warmest words about the Prince of Wales on record, she could clearly not have been prouder.
In a toast to celebrate the Prince's 70th birthday, the Queen has delivered a fond, heartfelt tribute to her son: an "heir to the throne to stand comparison with any in history" and, she joked, a true "Duchy Original".
Her words, in a family not known for their gushing sentiments in public, were remarkable, coming at a dinner in the ballroom of Buckingham Palace thrown in the Prince's honour.
The Prince himself, dapper in black tie with the Duchess of Cornwall on his arm, was surrounded by friends, family and European royalty, in a private celebration at the end of several weeks of very public birthday activities.
Amid the festivities, attended of course by the Duke and Duchess of Cambridge and Duke and Duchess of Sussex, were the warm words of the Queen, the crowning moment in a 70th birthday which has seen many members of the public think ahead to how the Prince may one day serve as King.
The Duke of Edinburgh, who has been missing from the Queen's recent public duties at the age of 97, took his rightful place at the table, along with his three other children and their spouses, to hear of the shared parental pride at watching the Prince of Wales' public work grow.
Those words, which will no doubt have touched the Prince deeply, were not without humour, making knowing reference to the his love of nature and, in a neat pay-off, his own range of organic food.
"It is a privilege for any mother to be able to propose a toast to her son on his 70th birthday," the Queen said in a toast.
"It means that you have lived long enough to see your child grow up. It is rather like - to use an analogy I am certain will find favour - planting a tree and being able to watch it grow.
"My mother saw me turn 70, of course. And she was heard to observe that 70 is exactly the age when the number of candles on your cake finally exceeds the amount of breath you have to blow them out.
"Over his 70 years, Philip and I have seen Charles become a champion of conservation and the arts, a great charitable leader - a dedicated and respected heir to the throne to stand comparison with any in history - and a wonderful father.
"Most of all, sustained by his wife Camilla, he is his own man, passionate and creative.
"So this toast is to wish a happy birthday to my son, in every respect a Duchy Original."
The toast was particularly significant for its recognition of the Prince as a father and the inclusion of specific praise for the Duchess of Cornwall, after a difficult 2017 which saw the 20th anniversary of the death of Diana, Princess of Wales, bring the most traumatic moment of the modern royal history into sharp focus.
The Duchess offered her own personal tribute ahead of the birthday, published in the Telegraph, while the Dukes of Cambridge and Sussex hailed their father affectionately in a BBC documentary made especially for the milestone.
As the Prince and Duchess left their London home of Clarence House together last night, ready for the short drive to Buckingham Palace, they looked the picture of happiness, the Duchess wearing diamond necklace, bracelet and earrings to accessorise a navy blue gown.
The women of the Royal Family had spared no effort or expense, with the Duchesses of Cambridge and Sussex dripping with sparkling diamond earrings and chic up-dos while their husbands, each driving them, in black tie.
The guest list, which is thought to have stretched to several hundred for dinner, reportedly included the grand royal houses of Europe, from Norway, Denmark, the Netherlands, Spain and Belgium, as well as the wider British royal family.
It was rather a far cry from the Prince's daytime activities, which saw him undertake meetings with visiting foreign politicians before the celebrations could begin.
In the afternoon, he had made a guest appearance a tea party for 70 septuagenarians who volunteer for charities close to the heart of the Prince and Duchess, including the Prince's Trust, the Silver Line, Maggie's and Barnardo's.
On his way in, presented by a small gift of a spray to deter grey squirrels from his beloved bird tables and a balloon, he joked that he was feeling, quite simply, "older".
"It's rather like indigestion," he said. "'Many Happy Returns' are not quite the same as you get older."
Asked by members of the press whether he would be slowing down at 70, the Prince said: "You may see it, slowly but surely."
The Duchess of Cornwall, unable to resist, chimed in: "I doubt it."
On the question of his birthday present, the Duchess said she had eventually found just the thing before insisting "I'm not telling" what it was.
Inside Spencer House in London, where the tea was swiftly replaced by glasses of champagne for those who wanted it, the Prince was serenaded with a rousing rendition of "happy birthday" before a group photograph.
"I was asked just now outside whether I was going to slow down," the Prince said, conceding: "I'm not sure I've got much alternative."
Fellow guest Gillian Ackers, who volunteers as a home visitor for the RSPCA and undertakes weekly visits to schools to help reluctant readers, said: "I am so pleased that Charles has chosen to spend his birthday meeting other 70 year-olds.
"Since I retired at 70 I try to keep busy. If I had one piece of advice for the Prince on his birthday it would be that he should not stop working."
Earlier that day the House of Commons and the House of Lords had both heard glowing tributes to the Prince.
Theresa May, the Prime Minister, said the heir to the throne had spent his life "defying expectations and refusing to be categorised", adding: "His commitment to public service has been total."
Jeremy Corbyn, the Labour leader, joked that he had considered offering jam from his allotment as a birthday gift but had since suffered a "deep crisis of confidence".
Sir Vince Cable, the Liberal Democrat leader, said: "As somebody who crossed the milestone of a 70th birthday some years ago, I'd suggest this is very much an opportunity for celebration rather than regret - and if I could add from personal experience that it shouldn't represent a glass ceiling for progression to a bigger job."