The Queen – the nation’s longest serving monarch – will have reigned for 25,000 days on Saturday.

Elizabeth II became sovereign on February 6 1952 on the death of her father, King George VI, when she just 25.

She will have been monarch for 68 years, five months and 12 days by July 18, and in 2015 overtook the record of 23,226 days, 16 hours and some 30 minutes set by her great-great-grandmother, Queen Victoria.

The Queen’s approach to having been on the throne for 25,000 days will undoubtedly be a matter-of-fact one, with the milestone unlikely to be on her radar.

When she became the country’s longest-serving monarch in 2015, she thanked the nation for its kind messages, but admitted that the royal record was “not one to which I have ever aspired”.

“Inevitably a long life can pass by many milestones. My own is no exception,” she remarked.

The Queen will be at Windsor Castle with the Duke of Edinburgh and the “HMS Bubble” of staff who have been running the couple’s reduced household.

A Buckingham Palace spokesman said: “The Queen is spending the day privately.”

The milestone falls the day after the monarch is welcoming Captain Sir Tom Moore to Windsor for a special investiture.

The 100-year-old fundraiser is being honoured with a personal, open-air ceremony in the castle quadrangle – believed to be the first occasion of its kind – as he is knighted by the Queen for raising millions for NHS charities.

The Queen, 94, has been seen riding at Windsor during lockdown and celebrated both her actual and official birthdays, as well as the Duke of Edinburgh turning 99.

She is less than two years away from celebrating her Platinum Jubilee – 70 years on the throne – in 2022.

The Queen reached her Silver Jubilee in 1977, Golden one in 2002 and Diamond Jubilee in 2012.

The monarch has been a figure of continuity as her country changed through the 20th century, the Millennium and into the 21st century amid new technological and social advances and a succession of British governments.

During the seven decades of her reign, man has landed on the Moon, Britain got its first, then second, female prime minister, the internet was invented, and gay marriage was legalised in the UK.

The public has looked to the Queen in times of tragedy – the September 11 terror attacks, the London bombings, the death of Diana, Princess of Wales, and more recently during the coronavirus crisis.

But even she confessed of the global Covid-19 pandemic: “While we have faced challenges before, this one is different.”

The Queen has delivered two rare televised addresses to the nation just weeks apart during lockdown.

She reassured the country that the virus would be overcome, telling those in isolation: “We will meet again.”

In another speech to mark the 75th anniversary of VE Day, she told how the message at the end of the war in Europe was “never give up, never despair”.

As well as being the longest-reigning monarch in British history, the Queen is also the longest still-serving sovereign and wealthiest Queen in the world, and the oldest British monarch.