Queen Elizabeth was "as radiant, knowledgeable and fascinated by politics" when she met Boris Johnson during his final meeting with the monarch on Tuesday, the former British prime minister said on Friday.
Johnson called on the Queen on September 6 at her Balmoral estate in Scotland to formally offer his resignation to pave the way for Liz Truss to succeed him as the new prime minister.
Johnson said the 96-year-old Queen was "as radiant, knowledgeable and fascinated by politics as I can remember and as wise in her advice as anyone I know, if not wiser".
"That impulse to do her duty carried her right through to her tenth decade to the very moment in Balmoral, only three days, ago when she saw off her 14th prime minister and welcomed her 15th.
"With her attentive and enquiring mind she became the greatest statesman and diplomat of all," Johnson was quoted as saying by the BBC.
Former Prime Minister Theresa May said audiences with the "immensely knowledgeable" Queen were the only meetings as a leader where everything that was said would remain private.
She said the meetings involved "talking about the affairs of the day, in a sense tapping into her wisdom and that knowledge that she had from her great experience".
The Queen would pass on "the knowledge that she had of the people, a lot of the people that the prime minister, that I, was dealing with," May told BBC's Radio 4 Today program.
"She was a very acute judge of people and was able often to give those little if you like, pen portraits of people that she knew, that she'd met.
"And sometimes it was a case of not just the individual but actually a sort of history of that individual, of her experiences of particular countries, particular issues."
"There was often that twinkle in the eye, and that magnificent smile that would break out and that calmed so many people's nerves and made so many people feel at ease," she said about the Queen, who died on Thursday.
Naturalist and broadcaster David Attenborough - a contemporary of the Queen - also paid tribute to the monarch.
"The Queen had an extraordinary ability to put you at your ease. If there was a technical hitch she wanted to know what it was and, if it had a funny side, she was quick to see the joke," he said.
(Inputs from PTI)
