Boris Johnson revealed he choked up when the BBC asked him to describe Queen Elizabeth in the past tense.
The former prime minister spoke in the Commons for the first time from the back benches after he resigned on Tuesday.
Johnson delivered an uncharacteristically emotional and personal tribute to the monarch, who passed away on Thursday.
MPs across the political spectrum paid tribute to the Queen as the United Kingdom entered a ten day mourning period.
Johnson told MPs: “A few months ago the BBC came to see me to talk about Her Majesty the Queen, and we sat down, the cameras started rolling, and they requested that I should talk about her in the past tense.
“I am afraid I simply choked up and I couldn’t go on. I am really not easily moved to tears, but I was so overcome with sadness that I had to ask them to go away.
“I know that today there are countless people in this country and around the world who have experienced the same sudden unexpected emotion.”
Johnson said that the Queen was “as radiant and as knowledgeable and as fascinated by politics as ever” at their last meeting before his resignation.
He said: “That impulse to do her duty carried her right through into her 10th decade to the very moment in Balmoral, as my right honourable friend [Liz Truss] has said, only three days ago, when she saw off her 14th prime minister, and welcomed her 15th.
“I can tell you in that audience she was as radiant and as knowledgeable and as fascinated by politics as ever I can remember and as wise in her advice as anyone I know, if not wiser.”
He praised the Queen’s “humility” and “refusal to be grand” and sparked laughter from MPs when he said: “Unlike us politicians, with our outriders and our armour-plated convoys, I can tell you as a direct eye witness that she drove herself in her own car with no detectives and no bodyguard, bouncing at alarming speed over the Scottish landscape to the total amazement of the ramblers and the tourists we encountered.”
Praising the “indomitable spirit with which she created the modern constitutional monarchy”, he added: “The fact that today we can say with such confidence ‘God Save the King’ is a tribute to him, but above all to Elizabeth the Great, who worked so hard for the good of her country, not just now but for generations to come.”
Former prime minister Theresa May also paid tribute to the Queen during the special Commons debate.
She said: “Queen Elizabeth II was quite simply the most remarkable person I have ever met.”
May added: “Across the nations of the world, for so many people, meeting Queen Elizabeth simply made their day and for many will be the memory of their life.
“Of course, for those of us who had the honour to serve as one of her prime ministers, those meetings were more frequent with the weekly audiences.
“These were not meetings with a high and mighty monarch, but a conversation with a woman of experience and knowledge and immense wisdom.”
From Winston Churchill to Liz Truss, 15 prime ministers served the Queen throughout her 70-year reign.
The Queen would have regular contact with the prime minister of the day and weekly audiences with them at Buckingham Palace.
The prime minister would be expected to keep the Queen informed about matters of national importance.