She will be 94 years of age in April and, like all nonagenarians, the Queen will surely look back on the momentous changes she has seen over her lifetime.
But I wonder if she will dwell most especially, not just on the big moments of history - the rise and fall of Hitler and Stalin, the coming of the welfare state, the growing influence of Asia - but on all the intimate details of her family life, and how much social values have altered since her birth in 1926.
I imagine that Elizabeth, like others who have attained great age, will reflect that many of the changes she has seen have been improvements. The world in which she grew up could be mightily stuffy and repressive. But there is one issue which she will, surely, weigh with some serious private thoughts, because it seems to be running amok through the family now - and that is the question of divorce.
Three of her four offspring have been through the divorce courts, and now it's cascading down the next generation. Her eldest grandson Peter Phillips is splitting up with his wife, the Canadian-born Autumn Kelly (whose own parents are divorced, as, of course, were Peter's parents, Princess Anne and Mark Phillips). Her nephew David Linley, Earl of Snowdon, also announced that he and his wife Serena were to part after 26 years of marriage.
His parents, Princess Margaret and the first Earl of Snowdon, were also divorced after a turbulent marriage. And that, Elizabeth might be thinking, is where the trouble began, when her sister Margaret was forbidden to marry the divorced man she was in love with, back in 1955.
It would not be an exaggeration to say that Elizabeth was brought up with a horror of divorce. Her mother, the old Queen Mum, who died in 2002, was an Episcopalian Scot who deplored the dissolution of marriage, which she associated with irresponsible men and fast women. The abdication of her brother-in-law Edward VIII, which rocked the monarchy, was all caused, in her eyes, by the machinations of an immoral American divorcee.
Princess Elizabeth would have been schooled in the tradition that matrimony was for life, "signifying unto us the mystical union that is between Christ and his Church", as her prayer book put it: what God hath put together let no man pull asunder. Personally, she would surely have adhered to that view - she has seldom failed to mention her Christian faith in her annual broadcast. But socially, and publicly, she has had to accept that times and values have changed. She has always believed it was right to do her duty, but "duty" isn't a word much in currency in our time. The "right to happiness" must seem to her to have superseded the call of duty. And yet, she may have asked herself, as a mother, where she went wrong.
Experience may also have prompted her to revise some of her earlier views.
The divorce of the Prince of Wales was another rocky time for the family and Camilla was initially hated by some members of the public, seeing her as the wicked mistress who had caused Diana's unhappiness.
But as time went by, Elizabeth came to accept Camilla and perhaps has even come to see that she is a better match for Charles (and he should have chosen her in the first place).
People do change their minds in the light of experience - and in both directions. An Irishwoman I know who vigorously supported the campaign for divorce in Ireland lamented to me last year: "Young couples these days don't seem to stick with a marriage. A bump on the road and they think they should split up."
Grandmothers and great-grandmothers may see marriage breakdown differently from younger couples. They may understand the strains of a difficult relationship, but they worry about the wider implications for the children and the family.
The grandmother generation also understands there can be "bumps on the road" in a marriage, but in the longer view, there can also be recovery.
With the continuing turbulence among the royals, the sentiment you hear most strongly expressed these days is: "I feel really sorry for the Queen - in her old age, coping with all these family problems".
As well as the procession of broken marriages, the sleazy narrative around Prince Andrew, her favourite child, must have hurt deeply. Then Harry and Meghan bustle off to Canada, carrying little Archie with them. She has accepted that, just as she accepted that Meghan was also a beguiling American divorcee, but their decision still looks like a snub.
There's a bit of steel in the old dame yet, however, and she's not letting them get away with branding themselves the Sussex Royals while rebuffing everything that her royal brand stands for. Privilege goes with duty!
A recent survey claimed that people reach a kind of serenity at around the age of 82. A philosophical attitude can replace anxiety and hand-wringing about the world's state of chassis. Towards the end of his life, my husband would greet almost every new sensational announcement with the reflection, "Twas ever thus". Old Irish people used to accept all events with the words "Tis the will of God". Perhaps Elizabeth has attained a similar cast of mind.