By merely being born, approximately on schedule, the new Baby Cambridge has performed the vital duty of taking Britain's mind off elections, tragedies, scandals and the fate of Jeremy Clarkson. Presumably the Duke and Duchess did not plan their second child's arrival for the run-up to polling day, but the timing - with its healthy whiff of royal insouciance - reminds us also of how serenely The Firm floats above the passage of lesser events.
At the moment, the Royal family is in remarkably good shape - its once-waning popularity restored, the Queen, at 89, widely admired, and its future seemingly assured.
This isn't simply a result of the new generation learning lessons from the past. When times are tough in a nation's history it looks for certainties.
The familiar, the reliable, even the faintly boring, become sources of solace, and a royal birth is a reassurance that nothing has changed as much or as badly as we fear it has. From that private room in a Paddington hospital comes a tiny voice of dissent against the gloom and worries of the world. It is a voice of hope and continuity, and its source, of course, will be too cute for words. Which is a further complication.
This is a world of baby-adulation-mania, in which an earnest magazine such as Forbes can publish an assessment of "the world's most influential babies", and websites like Babyrazzi pursue with awesome diligence the offspring of the super-famous. The leading publication in the business, People magazine, knows a hot tot cover can outsell any celebrity parent, and that a royal baby will be the biggest seller of all.
One day, when she grows up, perhaps into a saner world, the new arrival may wonder what all this interest amounted to, but for now she can only live with it. The public wants its baby's worth, and the modern Royal family has an incentive to oblige. In his first year, the new baby's big brother, Prince George, travelled nearly 30,000 miles, and performed a number of public engagements including taking possession of a stuffed wombat from the Governor General of Australia. The result was the virtual routing of Australian republicanism, and the conclusion - not lost on the shrewd minds at Court - that babies make friends.
They also lift morale, create business opportunities and, possibly, sway poll results. The Duchess's pregnancy was announced in September, days before the Scottish independence referendum, at a time when the Nationalists appeared to be gaining the ascendancy. Almost immediately, the polls swung back in favour of keeping the Union.
There seems, indeed, to be little that a royal baby can't do. "Births in the Royal family are a cause for celebration, and this can spill over into the stockmarket," explains Colin Cieszynski, chief strategist at CMC Markets.
One explanation is that a birth gives a boost to the broader UK economy, with champagne being popped and parties held, while impulse purchases of everything from clothes to cars tend to rise. The birth of Prince George in 2013 was estimated to have put almost a quarter of a billion pounds into the economy. What all this suggests is that the mood-shaping power of a royal birth has been seriously underestimated, and certainly under-used, for centuries.
In the old thinking, royal offspring had a purpose first and a life second. Within their families they were seen not so much as real children as dynastic jigsaw pieces, there to be slotted into the fiendishly complicated board game of alliances and hierarchies that kept an agreeable balance between the crowned heads of Europe. Such pampering as they received was mere preparation for official duties. The accounts of the Tudor court show that Henry VIII had two state-appointed cradle rockers, each paid £3 a year, and a rota of wet nurses on £10, but we also know the boy was brought up under suffocating restrictions, imposed by his father to keep him - and the dynasty - safe from harm.
Henry's own daughter, the future Elizabeth I, was sent away to the country at the age of three months with a household that included nurses, governesses, dressmakers, even a private secretary. She became one of England's greatest queens, but her reign strengthened the idea that a tough upbringing made for a better monarch. It wasn't necessary for anyone to see royal children, just to know that they were there. "It wasn't that these kings and queens didn't love their children," says David Cohen, a London psychologist and author of a book about royal upbringings. "They absolutely believed they were doing the right thing, in preparing them for the life that lay ahead. They didn't know any other way. Everything was dictated by the idea of keeping the monarchy, and, to their way of thinking, the country on the right track."
And so the model endured, little changed, to Prince William's time. The first real blows to the system of child-rearing were delivered by Diana, Princess of Wales, who was determined - as the Duchess of Cambridge is now - that her children should not only have a warmer, gentler introduction to royal life, but a fuller sense of life beyond. William and Harry accompanied their parents on overseas trips, were taken to pop concerts and amusement parks and largely spared the attentions of redoubtable royal nannies.
Even so, Diana had to battle against the Court's stiffer element, which believed that the spectacle of a future king or queen being shown off in the innocence of infanthood would fatally damage the "mystique" at the heart of the monarchy.
Today, a royal baby is part of The Firm from day one, and while this is partly down to the "flattening" of society, much of it flows directly from the middle-class mores of the Middleton family.
A baby may be royal, but it is still a baby. The Duchess, daughter of a party-supplies entrepreneur and a former air hostess, appears to grasp this intuitively, and the country shows every sign of sharing her thinking.
Now approaching his second birthday, George - to the frustration of his admirers - isn't, actually, seen in public very often, but when he does appear he seems remarkably like any other child of his age.
Those useful "royal sources" stress the parents' intention to give him a "normal" upbringing, far removed from the governesses and draughty prep schools of the past.
Thus the public's affection is extended into boyhood, youth, early adulthood . . . and the fulfilment of destiny. Cuteness now, goes the modern Buckingham Palace thinking, will be acceptance later.
All this begins on a single day, with ranks of cameras outside St Mary's hospital and a worldwide media operation ready to bring the first details to a world panting for news. Then comes the first picture of the happy parents with their prize and many people will rejoice - expensively - and with perhaps more of a consequential effect than it realises.
Like everything else in a successful monarchy, the process of replenishment must evolve. The new royal arrival can't know it yet, but all those people noisily cheering are telling her that her career is already under way.
With the new daughter of the Duke and Duchess of Cambridge being fourth in line to the throne, her birth could herald a significant change in the life of Princess Beatrice.
According to UK law, the first six members of the royal family in line to the throne must obtain the Queen's consent before marrying.
But the new birth means the first daughter of the Duke of York and Sarah Ferguson has moved from sixth to seventh in line to the throne and will not have to ask her grandmother's permission before choosing a spouse.