Watch Queen Elizabeth remembered: 'A record breaker & the longest reigning monarch in British history'

Britain's longest-reigning and longest-lived monarch was born on April 21, 1926, and spent 70 years on the throne before her death in September 2022 at the age of 96.

Such is Elizabeth's enduring impact that a YouGov survey last week found that 81% of those polled had a positive opinion of her, more than any living member of the royal family.

Robert Hardman, the royal author who this month published a new biography of the late monarch - "Elizabeth II: In Private. In Public. The Inside Story" - to mark her centenary, put her enduring appeal down to her "timelessness".

"There was a real sense that she connected with history but that she was also in touch with the present and that made her, I think, uniquely appealing to all ages," he told Reuters in an interview on Monday (April 20).

To mark the anniversary of her birth, Charles and Camilla will visit a new exhibition, "Queen Elizabeth II: Her Life in Style," which is currently being held at Buckingham Palace.

On Tuesday (April 21), the king and other royals will visit the British Museum to view the final designs for a national memorial to his mother, while Charles' sister, Princess Anne, will officially open the Queen Elizabeth II Garden in London's Regent’s Park.

In the evening, Charles and Camilla will host a reception featuring representatives from charities his mother supported as well as a number of people who will be celebrating their 100th birthday.

The royals' commemorations come after the government announced on Sunday that a new independent charity, the Queen Elizabeth Trust, was being launched to focus on restoring shared spaces in communities, backed by 40 million pounds ($54 million) with the king as its patron.

"Support for the monarchy generally is as it was during her reign is now... it goes up and down a little bit, but it's pretty much a flat line on the graph because... the king, I think, has confounded his critics when he started his reign," Hardman said, citing a recent opinion poll.

"The vast majority of people in Britain are comfortable with having a constitutional monarchy."

During Elizabeth's 70 years on the throne, Britain underwent dramatic change.

The austere postwar 1950s gave way to the swinging 60s, the divisive leadership of Margaret Thatcher in the 80s, Tony Blair's three-term New Labour era, a return to economic austerity and then the COVID-19 pandemic. "Essentially, she managed decline for 70 years while enabling Britain to sort of hold its head up high. At the end, I think she did leave it in a very solid state," Hardman said.

From Prince Harry and his wife Meghan stepping down from their roles and then criticising the institution from the U.S. to the fall from grace of his uncle, Andrew Mountbatten-Windsor, who has lost all his titles and been ejected from his home over his links to the late convicted U.S. sex offender Jeffrey Epstein, the royal family has been at the centre of high-profile dramas.

"Of course, at the moment we talk about the Andrew saga or the Harry and Meghan saga. These are live issues of the moment. But I think when in 50 years time, when historians looking back at the totality of her reign and what she did and how she steered Britain through many rocky periods, I think those will be second order issues compared to the big picture," Hardman said.