Liz Truss recalled how the Queen shared her “deep experience of government” when the pair met at Balmoral earlier this week, as she hailed the late monarch as “the rock on which modern Britain was built”.

The prime minister offered her condolences to King Charles III in a phone call on Thursday night and pledged to him her “loyal service” in “our new Carolean age”.

Two days of tributes began on Friday in parliament, with MPs in morning dress sharing touching and humorous experiences of meeting the Queen – including Boris Johnson.

Truss said Queen Elizabeth was “one of the greatest leaders the world has ever known” and that the UK was a great country “because of her”.

Recalling that the Queen’s first prime minister, Sir Winston Churchill, said King George’s VI death had “stilled the clatter and traffic of 20-century life”, Truss said that 70 years later, “life has paused again”.

She added: “As we meet today, we remember the pledge she made on her 21st birthday to dedicate her life to service.”

To murmurs of “hear, hear”, Truss said: “The whole house will agree – never has a promise been so completely fulfilled.”

The Queen took her red box of papers every day and gave royal assent to countless pieces of legislation, Truss told the House of Commons.

“She was willing to have fun,” said Truss, referring to the Queen joining Paddington Bear for tea to mark her platinum jubilee and appearing alongside Daniel Craig’s James Bond at the London Olympics opening ceremony in 2012.

The prime minister said the country owed King Charles “our loyalty and devotion”. Concluding her remarks, Truss said: “The crown endures. Our nation endures. And in that spirit, I say: God save the King.”

Other prime ministers, who had weekly audiences on Wednesdays with the Queen, also shared intimate details of their past encounters.

Theresa May recalled a picnic at Balmoral, detailing how she employed the three-second rule with some cheese she dropped on the ground.

“I had a split-second decision to make,” May said, admitting she returned the cheese to the table. MPs burst out laughing when she added: “I turned round to see that my every move had been watched very carefully by Her Majesty the Queen. I looked at her. She looked at me and she just smiled. And the cheese remained on the table.”

May also joked that her meetings with the Queen were the only ones she knew “would not be briefed out to the media”. She said the events were “not meetings with a high and mighty monarch, but a conversation with a woman of experience and knowledge and immense wisdom”, and added: “I doubt we will ever see her like again.”

Johnson made his first contribution as a backbencher since departing Downing Street and meeting the Queen for the final time.

“She saw off her 14th prime minister and welcomed her 15th.” he said. “And I can tell you in that audience, she was as radiant, knowledgeable and fascinated by politics as ever I can remember, and as wise in her advice as anyone I know – if not wiser.”

Johnson revealed that the BBC had interviewed him about the Queen “a few months ago”, and he was asked to “talk about her in the past tense”.

He admitted: “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.”

The Queen had a “special, personal relationship with us all”, the Labour leader, Keir Starmer, said. “Covid closed the front doors of every home in the country, it made all our lives smaller and more remote … At the time we were most alone, at a time we had been driven apart, she held the nation close, in a way no one else could have done. For that, we say ‘thank you’.”

Starmer said the Queen “would want us to redouble our efforts, to turn our collar up and face the storm, to carry on”, and added the late monarch “will always be with us”.

Harriet Harman, the longest-serving female MP, told how, when she was sacked after just a year in the cabinet and “nobody else wanted to know me”, the Queen invited her for tea. She “marvelled” at the Queen for her “determination and courage” by challenging the status quo when she took to the throne in 1953 in “what was emphatically then a man’s world”.

Tributes in parliament will continue from 1pm on Saturday, following some senior MPs taking the oath of allegiance to King Charles III.