From her private offices on the second floor of Buckingham Palace, the Queen's prospects for 2018 could hardly look better. She remains – even at 92 – in formidable good health; there is a new royal baby; and Prince Harry, once considered something of a dynastic liability, is fully rehabilitated and has married Meghan Markle. No whiff of scandal currently swirls around the palace parapets, and opinion polls show that the monarchy is enjoying a golden period of popularity.
Yet behind the walls of the sovereign's official residence hums a royal machine which knows this is no time for complacency. The year's marquee events will have little long-term bearing on the serious challenges that lie ahead. Power shifts are underway, egos are clashing, deals are being cut, and no one doubts that the remaining years of the Queen's reign will determine whether the House of Windsor has a future.
The biggest problem, as courtiers acknowledge, is even imagining life after Elizabeth. Already the longest-reigning British monarch in history, and revered everywhere as the embodiment of duty and service, the Queen is simply irreplaceable.
"The modern monarchy is Elizabeth II," says Philip Murphy, director of London's Institute of Commonwealth Studies.
"We have no other models. In a long, turbulent era, she has come through everything. When she goes, all bets are off."
To lessen the chances of anything going badly wrong, the Court's brightest minds are already making subtle adjustments to the royal order. The most visible evidence of change is a reduction in the Queen's duties and the promotion of her heir, Charles, the Prince of Wales, who was last year the busiest of the royal family with almost 550 official engagements.
Not that the Queen is taking it easy. A typical working day remains a blur of activity. At 7.30am she will be awoken by a chambermaid bearing a pot of Twinings English Breakfast tea and fresh milk from her own herd of Windsor Castle cattle. She will scan the day's newspapers, and by 10.30am, when she holds her morning meeting with her private secretary, Edward Young (the man who talked her into the James Bond parachute stunt at the 2012 London Olympics), she will have been through her daily briefing papers and read a cross-section of the 300 or so letters she receives each morning.
Then things start moving; audiences, investitures, receptions. Lunch may be in private or with guests, and when it is finished, the Queen will be off for a round of afternoon engagements. By early evening she is back, but far from finished. There are evening galas and concert performances to attend, official papers to read and, always, more people to meet. What astonishes everyone who follows Elizabeth's life is not so much that she can keep this up at her age, but that she does so without ever making a mistake or letting the slightest glimmer of boredom show.
"Given the strangeness of her life," says author Gyles Brandreth, a friend of her 96-year-old husband, Philip, the Duke of Edinburgh, who has observed the royal couple at close quarters, "she seems to be remarkably well-balanced. She is awesomely sane and wonderfully grounded. It would be fascinating to know what she really thinks."
Outwardly, the Queen remains inscrutable – one of the best and least known women on earth. Part of the problem of understanding her thoughts is that hardly anyone talks to her informally, and those who do are usually too awed to remember much about it. Prominent British journalist Dominic Lawson – brother of celebrity cook Nigella – recalls being "seized by a kind of gibbering terror" when invited to one of the Queen's occasional lunches for movers and shakers. "I haven't the faintest idea what we talked about," he says.
There is no question of her abdicating. Seventy years after the young Princess Elizabeth broadcast to what was then the Empire, "I declare before you all that my whole life, whether it be long or short, shall be devoted to your service," she is still delivering on the promise. Yet even this redoubtable woman cannot defy age indefinitely, and she has recently seen at close quarters the attractions of slowing down.
The Queen's winter sojourn at Sandringham, the royal estate in Norfolk, was her first since Philip's retirement last year from official duties. The Duke – recovering from his recent hip surgery – lives now at Wood Farm, a large, comfortable cottage on the estate, where he paints, reads, writes letters and entertains old friends. A small staff, including a valet and a secretary, looks after his needs, and by all accounts, Philip has found a new contentment away from the grind of royal service.
The arrangement means, however, that the Queen is having to manage without him for the first time in their seven-decade marriage. She has never disguised the extent to which she has depended on his support and advice – paying a particularly warm tribute to him in her last Christmas broadcast – and for all her stoicism, it is hard to believe she doesn't miss having him at her side.
Her job has consequently become lonelier and harder to do. But even Philip's reassuring presence at the palace would not forestall the problems quietly piling up behind the monarchy's veneer of wellbeing.
Approaching 70, Charles is the oldest heir in British history. Polls suggest he is also, by some way, the least popular of today's senior royals, with an approval rating of barely 40 per cent. His future subjects claim to find him "odd" and "cranky" and many still blame him for the unhappiness and untimely death of his former wife, Diana, Princess of Wales.
This feeds directly into what one courtier calls the "unexploded bomb" ticking beneath the royal household – the issue of whether Charles' second wife, Camilla, the Duchess of Cornwall, can ever become Queen. For years, the calming guidance from senior palace staff has been that Camilla will be given the title "Princess Consort", but Charles is understood to resent this idea, believing that a lesser honour would be a slight to the woman he has loved for his entire adult life.
"He feels that if he has waited this long to be King, he's at least entitled to have a real queen at his side," says the duchess's biographer, Caroline Graham. "No one's really sure how this can be resolved. Camilla, of course, would love to be Queen."
Late last year, the Queen's most senior aide, her private secretary, Sir Christopher Geidt, abruptly left his job – reportedly after a series of rows with Charles. According to The Times newspaper, their main disagreement was on how best to manage the handover of responsibilities from the sovereign to her heir, with Charles demanding that the process be speeded up, but, significantly, Sir Christopher was known to be strongly opposed to the idea of Camilla becoming Queen.
This drama was followed by a startlingly candid article in the highbrow British political magazine, Prospect, headlined: "Will the reign of King Charles III bring down the monarchy?"
The piece went on to state: "Senior courtiers and high-ranking Whitehall mandarins privately share the fear that the Prince of Wales could morph into a meddling, dangerous monarch; an opinionated King who can't stop interfering in the issues of the day under the pretext of 'wanting to make a difference'. One who wants to re-mould the role from a stately, silent figurehead, decked out in fancy uniform, to that of a far more pro-active sovereign – potentially threatening the whole constitutional basis and future of the monarchy."
Phew! Even Charles' harshest critics have hesitated to suggest he might bring the whole caboodle down with him. But implicit in the suggestion of trouble ahead is the big question the post-Elizabeth British monarchy will have to answer – what is it for?
The Queen's immense standing has largely shielded the institution she leads from criticism. Even diehard republicans accept that the monarchy is invincible for as long as she lives.
But what then? Anna Whitelock, a university professor and author of an acclaimed biography of Elizabeth I, says the protection provided by the Queen may give a false impression of the monarchy's durability.
"All these questions about why we actually want a royal family and what it represents in the modern world have been held at bay by the Queen," she says.
"But they haven't gone away. Many of the young people I teach have grown up with a different idea of social equality, and don't see the justification for inherited status. By 2030, I think there will be loud voices clamouring for the abolition of the monarchy. I'm not saying there won't be a monarchy, but it will be questioned and challenged in a way it hasn't been before."
It is to address this threat that the royal establishment is working feverishly on a blueprint for the future – supposedly code-named "Project 70" because it is meant to be in place by Charles's landmark birthday in November. But no one pretends there are easy solutions, or even much agreement on the right approach. Progress has been bogged down by a long-simmering feud between traditionalists who dislike the easygoing, "feel-our-pain" bent of the younger royals, and modernisers who think the monarchy must be more reflective of today's society.
Princes William and Harry – both aligned with the modernisers – think a new template of royal life is necessary; one that makes a clear distinction between public and private roles. When Harry controversially claimed last year that "no one wants to be King or Queen", he was, say his aides, not being disrespectful, but expressing frustration at the difficulty of ever having a life away from the job.
"I don't think there's necessarily a conflict between the main players, the royals themselves," says Dickie Arbiter, a former palace press secretary, "but there is probably a conflict between the people behind them. There's a tendency for people who come into royal households from the outside to get a bit of red-carpet fever, to feel more important than they should do. So that's where you get the personality clashes, and it is not a good thing."
Occupying the middle ground of the argument are a significant number who believe the royal family is worrying too much.
"There were more people wanting to abolish the monarchy in Queen Victoria's time than there are now," says royal author Alison Weir.
"As long as the monarchy can keep people's interest and seem relevant, it will be secure. Give them credit. They've responded to criticism, brought themselves more up to date, and most of us think they do a pretty good job."
Greg Jenner, a British TV historian popular with young viewers agrees: "The Queen is amazing and a massive factor, but William and Harry and Kate have done excellent work in establishing themselves as the youthful, modern face of royalty. The monarchy has gone through much more turbulent times in the past. Look at the illness of George III, the debauchery of George IV, the abdication crisis with Edward VIII."
Further optimism comes from the remarkably good health of other monarchies across Europe. A generation ago, many of these ancient royal houses looked like the moribund remnants of an exhausted gene-tank, but a dose of democratisation and an influx of new blood has led to a Continent-wide revival.
A century ago, royal-to-commoner marriages were almost unthinkable. Now they barely raise an eyebrow. Crown Prince Frederik of Denmark met his bride-to-be, Australian office temp Mary Donaldson, in a Sydney pub. Sweden's Crown Princess Victoria married her personal trainer, a bespectacled fellow Swede who now styles himself as Prince Daniel, Duke of Vastergötland. King Felipe of Spain wed Letizia Ortiz, a TV presenter whose father was a Madrid taxi driver. Having spent decades smooching with starlets and canoodling with covergirls, Prince Albert of Monaco is now happily settled with Charlene Wittstock, a South African swimming champion.
"Our experience in Denmark, and across Europe, is that commoners bring excitement, and the people love the fairytale factor in these romances," says Copenhagen University sociologist Jens Henner. "There's an important further factor that in these troubled times, people cling to things that seem permanent and familiar; the monarchies have benefited from that."
There is no doubt the Queen deserves some credit for her deft tweaking of the royal tiller. There are some things she will never do – such as give an interview or queue at a supermarket check-out – but, overall, today's monarchy is a radically different and faster-footed beast than the one she inherited in 1952. Back then, the Court still adhered to the famous maxim of 19th-century constitutional writer Walter Bagehot: "Never let daylight in on magic."
The idea was that the monarchy would lose its mystique if people knew too much about it. Secrecy and concealment clouded every aspect of royal life, the rules were rigged to deter outsiders, and the idea of a prince marrying a movie star would have seemed absurd.
On May 19, Prince Harry will walk down the aisle of St George's Chapel in Windsor Castle with Meghan, a 36-year-old Los Angeles-born divorcee. It would be an exaggeration to say that everyone in the royal establishment is relaxed about the union, but there has been no serious opposition, and the Queen has been personally supportive.
If there are any blemishes on the sovereign's record, they show most vividly in the grown-up lives of her children, three of whom have been divorced. Charles' disastrous match with Diana brought the monarchy to one of its lowest points, but the lessons were learned, and the Queen now accepts that royal marriages cannot be the kind of dynastic board game played out in the Victorian era.
She has embraced changes to the succession, ending the preferential male claim, ensuring that the Duke and Duchess of Cambridge's daughter, Charlotte, is now fourth in line to the throne, behind only Charles, her father Prince William and brother Prince George.
And still Her Majesty powers on, determined that her legacy will be the survival of the monarchy. When the young Elizabeth was crowned in June 1953, a popular tribute was to plant a tree in her honour. Today those trees are big and strong enough to stand up to any storm that buffets them. Rather like the woman herself.