Boris Johnson Recalls Queen Elizabeth's Hilarious Reply to His Nightmare That He Was Late: 'Were You Naked?'

The former U.K. prime minister said audiences with Queen Elizabeth were both a "tutorial and a confessional, with a bit of unpaid psychotherapy thrown in"

Queen Elizabeth was known for being prim and proper, but she also didn't shy away from a good joke.

Former U.K. Prime Minister Boris Johnson reminisced on his time with the late monarch in an article for the Daily Mail as the first anniversary of her death approaches next week. Johnson was the 14th prime minister of Queen Elizabeth's historic 70-year reign, and the Queen's last public duty before her death was formally appointing Liz Truss as the new premier after Johnson stepped down.

Johnson wrote, "It was because of her humanity and sympathy that you felt, as PM, that you could really open up to her, tell her absolutely everything, so that the audiences were a mixture between a tutorial and a confessional, with a bit of unpaid psychotherapy thrown in."

"I once told her that I had a nightmare that I had been late for her and the Duke," he continued, referring to the Queen's husband Prince Philip, known by his title as the Duke of Edinburgh. " 'Oh yes,' she beamed, and I could tell that she had heard this one before, probably from other PMs. 'Were you naked?' she asked because it turns out that is a ­common feature of such dreams."

Related: Queen Elizabeth Tells Photographers to Move in Hilarious Unearthed Video: 'Do You Mind?'

The Queen "is much livelier in private than what the public sees," royal biographer Sally Bedell Smith, author of Elizabeth the Queen: The Life of a Modern Monarch, previously told PEOPLE.

The author quoted a source at the Queen's Sandringham estate once saying, " 'You can hear her laugh throughout that big house.' She has a big laugh!"

Remember his grandmother following her death, Prince Harry said in a statement, "I miss her dearly, as well as her cheeky sense of humor and quick wit."

Johnson recalled Queen Elizabeth allowing him to exercise in the Buckingham Palace gardens when he was recovering from an illness, and he said she had quite an impressive range of knowledge.

"We were grappling one day with the subject of Zambia, and I was trying to remember the name of the late President. 'Kenneth Kaunda,' she said instantly," he said. "Another time we were talking about the last English monarch to lead his troops into battle. I could remember the King — George II — but I couldn't ­remember the battle. 'Dettingen,' she said, like a pub quiz winner."

Johnson also remembered the "surreal experience" of visiting Balmoral, the royal residence in Scotland where Queen Elizabeth spent her summer months.

"All of her PMs have had the ­surreal experience of going to ­Balmoral, and watching Britain's longest-serving monarch as she prepares her special vinaigrette," he wrote. "We have accepted from her hand the sausages barbecued by the Duke of Edinburgh and tried to help her pack it all away in her special Tupperware boxes. I expect every PM has been pretty nervous on arrival."

He added, "The first evening we found a note on the bed for Carrie. 'Ma'am,' it said helpfully, 'Her Majesty will be wearing an ice-blue cocktail dress for dinner this evening.' I don't think Carrie had packed anything like an ice-blue cocktail dress, but it was a useful piece of information."

Queen Elizabeth's trusted aide and friend Angela Kelly previously discussed why the monarch's clothing choice was shared with other guests in her book, The Other Side Of The Coin: The Queen, the Dresser and the Wardrobe.

"Once Her Majesty has chosen her dress for dinner, a handwritten notice is pinned up in the Dressers' Corridor detailing what she will be wearing, so that The Queen's ladies' maids can select an appropriate dress for the lady they are looking after," she wrote. "When it comes to the Royal Family, it doesn't matter if they wear the same colour as The Queen because they are family, and sometimes the ladies will wear cocktail dresses even though The Queen might be wearing a long one."

She continued, "Other guests, though, feel they shouldn't be in the same colour as Her Majesty, although The Queen would not mind if this did happen."

Related: Queen Elizabeth and the Prime Ministers of Her 70-Year Reign — from Winston Churchill to Liz Truss

Johnson's piece noted that Queen Elizabeth had a great gift: "She could make you feel — whatever you were telling her — that you were really rather special and interesting; and then to flash that wonderful smile."

"When you were with her, you could see why the elderly ­Churchill had such a crush on her. You understood why Barack Obama was so entranced that he stayed up drinking with her so late, they say, that the footmen had to come and cough to indicate that the evening was at an end," the former prime minister said. "You felt that even though she had seen it all, knew it all, she also enjoyed and appreciated politics in all its intricacy and absurdity."

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King Charles and Queen Camilla are expected to spend the anniversary of Queen Elizabeth's death on Sept. 8 quietly and privately, as the late monarch used to do on her own Accession Day.

Westminster Abbey, where the coronations of Queen Elizabeth and her eldest son were held, will ring the bells will ring on Friday in honor of Charles’ Accession Day, according to the abbey. In another tribute, a 21-gun salute will be fired in the royal parks of London as a sign of respect on King Charles’ Accession Day, the royal family's website states.

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