She has reached many milestones in her 64 year-old reign, but one anniversary holds a special place in the Queen's heart. For it is the day, 80 years ago, that she made her first public speech.
Joined by Princess Margaret, her younger sister, on Oct 13 1940, a then 14-year-old Princess Elizabeth gave a wartime radio broadcast in which she addressed the children of the Commonwealth, many of whom were living away from home because of the war.
Wishing them "goodnight … and good luck", she said: "We know, every one of us, that in the end all will be well. For God will care for us and give us victory and peace. And when peace comes, remember it will be for us, the children of today, to make the world of tomorrow a better and happier place."
Buckingham Palace will no doubt be marking the moment the 94-year-old monarch first signalled a dedication to duty that has come to characterise her life on the throne.
And as she prepares to resume official engagements in London this week, that deep-rooted sense of obligation will once again be on display.
Having travelled to Windsor Castle on Tuesday from Wood Farm in Norfolk, where she has been hunkered down with the Duke of Edinburgh, 99, since mid-September, Her Majesty's arrival back in the capital is intended to signal a return to business as usual, after what has been a most unusual year.
Ordinarily, the couple would have remained at Balmoral Castle until now. Instead, they chose to end their summer at the relatively humble farmhouse on the Sandringham estate that has been the Duke of Edinburgh's main base since he retired from public life in 2017.
The move to the pared-down property was not only designed with economy in mind, but also as a result of Balmoral becoming a little tiresome without the typical steady stream of visitors.
Although family including the Princess Royal, the Wessexes and the Cambridges all came to visit, because of social distancing rules it simply wasn't as enjoyable as usual.
According to one insider: "It was a bit tedious at times – not just for the staff, but the royals themselves. Balmoral can sometimes be a little hard going, but coronavirus made things even more difficult. There was quite a lot of time spent sat around, twiddling thumbs."
The Queen's dedicated team of staff, nicknamed "HMS Bubble", were forced to self-isolate for two weeks before even travelling up to the Scottish Highlands.
Once there, they were banned from social activity and, with the annual Ghillies Ball cancelled because of Covid-19, had little to occupy themselves while off duty.
Starved of the usual social fixtures to keep them busy, employees were confined to a dull, granite accommodation building called New Block, which some took to calling "Colditz", after the prisoner of war camp.
Another source added: "Everyone got pretty bored. I think the Queen and the Duke went to Wood Farm simply for a change of scenery, more than anything else."
Although two teams made up HMS Bubble, and were regularly switched in and out, some aides, including Angela Kelly, the Queen's "right-hand woman", and Paul Whybrew, her personal page, are understood to have remained at her side since March.
It is thought that efforts were made to persuade the Duke to return with his wife last week to Windsor, where they spent the first five months of lockdown together. Instead, he has opted to remain at the five-bedroom Wood Farm, where he enjoys his independence away from the flummery of formal royal life, and spends most of his time in an armchair, reading.
His remaining in Norfolk while the Queen returns to her "court" signifies a return to some sort of normality for a stateswoman whose personal mantra has always been: "I need to be seen to be believed."
As one aide put it: "Buckingham Palace is a working palace and a symbol of working monarchy. The soft power of the Queen is never better demonstrated than when she is meeting foreign leaders and diplomats there.
"If you can do that at the palace, then it is desirable to do so." Hence why "select" audiences and other small gatherings – within the so-called rule of six – have been pencilled in to the Windsor diary. There is talk of the Queen's weekly discussions with the Prime Minister, which have been largely conducted by telephone during the outbreak, resuming face-to-face.
At this stage, the only major public event the Queen seems guaranteed to attend in person is the Remembrance Service at the Cenotaph on Sunday Nov 8.
Not only is it the one of the most firmly inked-in engagements in Her Majesty's diary, but it also carries extra significance this year, as it will be the 100th anniversaries of the unveiling of the Cenotaph war memorial in Whitehall and the Tomb of the Unknown Warrior in Westminster Abbey.
There have already been suggestions that attendance at this year's Remembrance Sunday commemorations will be massively scaled back, while the Festival of Remembrance, traditionally held the night before at the Royal Albert Hall and attended by the Queen and her family, will not go ahead in its usual format.
Quite how the rest of the time leading up to Christmas pans out also remains to be seen during what is being described by all behind palace gates as a "fluid situation". "Every decision we make is dependent on the latest restrictions, so like everyone else we are having to take it each day as it comes," said a source.
Discussions are already under way as to where the couple will spend Christmas – and even more crucially, with whom.
With the Duke having remained in Norfolk, it seems most likely the Queen will return to Sandringham as usual for the festive period the week before Christmas. She would normally travel up there by train from King's Cross to King's Lynn, but this seems unlikely in the current circumstances.
Yet with Christmas usually a major family gathering for the royals, the couple are going to have start significantly narrowing down the guest list. The Cambridges are likely to be the first to opt out, on account of being a family of five. It is thought they will spend the season of goodwill at Anmer Hall, their nearby Norfolk home.