Obamas with Duke and Duchess of Cambridge
Coming generation: the Duke and Duchess of Cambridge welcome Barack and Michelle ObamaGetty Images

I went to watch the Duchess of Cornwall open the new building of St Wilfred's Hospice, Eastbourne. It was just one of several events that this latecomer to the duties of the monarchy carried out that day.

Even I was astonished by the way in which the visit unfolded. First there was the thrill of anticipation and all the arrangements. And on the day itself, huge excitement, best clothes and hairdos, last-minute changes to the line-up, and then there she was: a middle-aged woman with a great smile and great gift for quick, kind conversations – and something extra, something indefinable but vital. Something almost magical.

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The Duchess went around the hospice, with just one member of her staff and at least half a dozen photographers, and talked, just talked, to the patients and the nurses who lined the corridors. To some she spoke of her own happy Sussex childhood, to others of their own lives. Many of them were in tears after they spoke to her, and even patients who knew they were about to die said how happy her visit had made them.

I came away shaking my head once more at the extraordinary power of the monarchy in this country. And I remembered that Martin Charteris, probably the Queen's most joyful Private Secretary, used to say: "The only point of monarchy is to increase, just a little, the sum of human happiness." That is what the Duchess of Cornwall had done in Eastbourne that day. There was something magical about it.

The fact that she was able to do just that explains why we still have a hereditary monarch. And the ultimate credit for it lies with the Queen, to be 90 in April 2016 and even sooner, this autumn, to become our longest-serving monarch ever, surpassing Victoria who reigned for 63 years, seven months and two days.

It is this Queen's devoted service over almost as many years, months and days that has assured the monarchy of its continued strength in Britain today. That
and the fact that magic still does accrue to the monarchy, even in an overwhelmingly materialistic, secular age.
Every country needs a head of state. The vast majority of the 193 members of the United Nations today are republics with presidents. Monarchies exist only in Japan, Thailand, Morocco and some Gulf states – and in Western Europe, where they are among the most stable democracies in the world.

Queen Elizabeth II: The life and legacy of Britain's longest reigning monarchIBTimes UK

In other words, monarchies are relatively unusual today. But, in an amusing conceit, Professor Vernon Bogdanor, a guru of constitutional history, has speculated that the rise of the republican model over monarchies might not have taken place had America broken from Britain slightly later. In the late 18th century, the parliamentary system was not yet fully developed and so the Founding Fathers decided that a constitutionalised monarchy, an executive Presidency,
was the only possibility for their revolutionary new state. Had America broken away 50 years later, after the Reform Act of 1832 (which was strongly supported by King William IV), the Fathers might have adopted a parliamentary system with a ceremonial head of state.

All systems have flaws. In America it is often hard to combine the role of head of government, the leader of the party that has just won an election, with that of head of state, representing the people as a whole. Thus America was deeply divided between those who supported President Nixon and those who loathed him, between those who thought President Bush a war criminal and those who believe Obama is a narcissist who has more faith in himself than in America.

Another presidential system involves an appointed president – as in Germany or Italy. These are often retired politicians who have been pushed upstairs. Sometimes they are fine and sometimes they are nonentities at home as well as abroad. When such a system held in France in the early 20th century, the statesman Georges Clemenceau advised: "Votez pour le plus stupide."

But there is nothing intrinsically wrong with republican government. The Duke of Edinburgh once said: "If the people want to change to a republic, that is a perfectly sensible alternative. It is a complete misconception to imagine that the monarchy exists in the interests of the monarch. It doesn't. It exists in the interest of the people."

The basic flaw in a hereditary monarchy is that it is a lottery. Any king or queen could be mad or bad or merely ineffective. For more than a century Britain has been blessed. Queen Victoria, who built the constitutional monarchy, died as the 20th century dawned. Elizabeth II's predecessors – great-grandfather, Edward VII, grandfather George V and father George VI – all served their country remarkably well. (Her uncle Edward VIII, who certainly would not have done so,
fortunately abdicated in 1936 before he was crowned.)

But the laurels for 20th century monarchy must clearly go to the Queen. She came to the throne on the early death of her father in 1952, when she was only 25, and she has presided over tumultuous change in her kingdom ever since. Indeed, she has been the one still voice of calm at the centre of the social and political storms that have raged in the past 60 years and more.

Today, it is fashionable on the Left (as it always has been) to say that monarchy is a relic of an old society which has outlived its time. This conviction demands a snobbish disregard for the opinions of people. Poll after poll, decade after decade, shows that, however much this kingdom changes, roughly 80 % of the country favour the continuation of the monarchy in Britain. We are at the moment in an extraordinary, almost unique position that demonstrates very well the unique strengths of monarchy.

We have a head of state, her heir and his heir all working together to represent the nation. No other country in the world has three people, in three generations of one family, dedicated to promoting the welfare of their nation. And never before has it happened here. Three people, from the monarch now aged almost 89, her son of 66 and her grandson at 32 (not to mention other members of the family from Princess Alexandra to the Princess Royal to Prince Harry), can
cover every age group and an astonishing range of interests in the country. It gives remarkable new strength to the institution – the vigour of the young members of the family complements the wisdom and experience of the older.

Recent years have seen a collapse in authority in almost all parts of British society. This has coincided with a growth in the power and influence of the media. The television interviewer Robin Day summed it up before his death: "Look at all our great traditional institutions – the monarchy, the Church, the judges, the police, the Bar, the BBC – every pillar of the established order. They seem now to inspire more ridicule than respect. It is due to an overwhelming sea change in attitude to authority , institutions, history, religion, tradition, law and ceremony. The age of deference, the age of reverence, is over."

That was more than 15 years ago – since then almost all the institutions which he mentioned enjoy even less respect. Except the monarchy. It went through a very bad period in the 1990s with the divorces of several of the Queen's children and the death of Diana, Princess of Wales. But since then the Queen has celebrated her Golden and her Diamond Jubilees and now the institution seems stronger than ever.

Jubilees are important moments in the British monarchy. Queen Victoria wrote in her diary of her Diamond Jubilee in 1897: "A never to be forgotten day. No one ever, I believe, has met such an ovation as was given to me ... The crowds were quite indescribable and their enthusiasm truly marvellous and deeply touching. The cheering was quite deafening and every face seemed to be filled with joy."

Our present Queen could have written similarly of the enthusiasm of the crowds at her Silver, Golden and Diamond Jubilees. But she is too modest. The same approval was shown to her grandfather, George V, at his Silver Jubilee in 1935, less than a year before his death. The King himself was much moved, saying: "I'd no idea that they felt like that about me ... I am beginning to think that they must really like me for myself."

Then as now, Left-wingers like Beatrice Webb harrumphed. George Orwell was, as usual, wiser. He argued that the loyalty of the crowds demonstrated "an idea almost as old as history, the idea of the King and the common people being in some sort of alliance against the upper classes".

George V's official biographer, Harold Nicolson, reckoned that the popular enthusiasm reflected their affection for " a strong benevolent patriarch" and "gratitude to a man who by his probity had earned the esteem of the whole world". Just like his grand-daughter, who has had to refashion the institution of monarchy to a much more demanding and unforgiving age.

That she has done so is a personal triumph for the Queen herself. To understand how she has done it, how she has preserved and indeed enhanced the dignity of the monarchy when so many other institutions have cracked and failed, one must try to understand what inspires her.
Consider these statements, delivered in the course of many decades.

In 1947, at the age of 21, "I declare before you that my whole life, whether it long or short, shall be devoted to your service ..."

In 1952, she asked the people to pray that on her Coronation Day "that God may give me wisdom and strength to carry out the solemn promises I shall be making, and that I may faithfully serve him and you all the days of my life".

In 1977, recalling her promise in 1947, "Although that vow was made in my salad days when I was green in judgment, I do not regret or retract one word of it."

In 2002, her Golden Jubilee, she told Parliament of her resolve to continue "to serve the people of this great nation of ours" – and the politicians gave her a standing ovation.

At Christmas 2012, the year of her Diamond Jubilee, she asked us to remember that God sent his only son "to serve, not to be served".

She too has served, decade in, decade out. She has, in her own words, taken every day "as a new beginning. I know that the only way to live my life is to try to do what is right, to take the long view, to give of my best in all that the day brings and to put my trust in God".

In all these words, two things stand out – the Queen's constant sense of duty and her devotion to God. Of this she speaks humbly but openly, especially in her Christmas broadcasts, her only speeches which are not scripted by the government.

In his exquisite book, England An Elegy, Roger Scruton writes that the constitutional monarchy is "The Light above Politics which shines down on the human bustle from a calmer and more exalted sphere".

The monarch is not elected and so does not represent any present let alone sectarian interest. He or she is in a real sense the voice of history. Kings may be mad or at least unwise but the important point is that they owe their authority to something other than the present desires of voters.

We saw that with particular intensity in June last year when the Queen stood on the Normandy beach of Ouistreham to celebrate the 60th anniversary of the D-Day landings. Around her stood all the politicians of today – some able, some not, some already gone. On big screens behind the Queen and other leaders the world saw photographs of her, a young woman in uniform, 60 years before as Allied forces landed on those Normandy beaches to begin the process of liberating Europe from fascist tyranny.

No other nation in the entire world can savour such continuity and sense of history as the Queen and the monarchy give Britain. As Paul McCartney said: "I grew up with the Queen, thinking she was a babe. She was beautiful and glamorous."

The other great quality of a successful monarchy is that it humanises and softens the state. This has been well explained by American historian Frank Prochaska, who has long studied the way in which the monarchy has sustained and enhanced civil society in Britain.

The first sentence of his book, Royal Bounty, the Making of the Welfare Monarchy, is straightforward. "No people on earth can lay claim to a greater philanthropic tradition than the British."

And why is that? Well, one very important reason is the role of the monarchy at the very heart of charitable giving.

At the end of the 18th century, the French Revolution and particularly the execution of Louis XVI led to widespread fear that republicanism could sweep Britain too. Under George III the concept of noblesse oblige took hold. He was a moral and decent man who loved his Queen Charlotte. Indeed John Wesley listed his virtues simply – "He believes the Bible ... he fears God ... he loves the Queen."

George III strengthened the link between the monarchy and philanthropy. When the King died in 1820 one divine declared that under his benevolent auspices more charities had been created "than had been formed during the whole period from the commencement of the era of redemption".

Through their associations with charity, the King and his family encouraged the spread of traditional values and a sense of social unity. As Prochaska pointed out, the accumulation of royal patronages in the reign of George III had transformed the monarchy's traditional charitable role out of all recognition. "The royal family, with little forethought, had become allied with ascendant middle England – respectable and patriotic."

What is remarkable is the fact that it is still the case today. What Prochaska called the welfare monarchy is still critical to the strength of the institution and underpins the role of the monarchy as the head of civic society. During the present Queen's reign there has been a revolution both in the composition of the population of Britain and in its attitudes. The Labour government of 1945-50 created the welfare state and thus usurped the traditional role of charities and their royal sponsors in providing for those in need, but the surprise of some and the dismay of many on the Left, royal-led charities did not fade away.

In 1962, 14 years after the NHS was created, there were 800,000 volunteers in one organisation of which the Queen Mother was patron, the National League of Hospital Friends. Richard Crossman, Labour Secretary of Health and Social Security, declared himself "staggered" by the extent to which the NHS depended on voluntary work. In the 1960s a Mass Observation survey showed how deeply the public still identified the Royal Family with its welfare role.

Perhaps even more importantly, the survey showed a widespread feeling the Crown was "a bulwark" against the danger of government taking away too many democratic freedoms. I would argue that that is even more true today when members of the Royal Family are the valued patrons of more than 3,700 charites and other organisations.

There are moments of tension in any constitutional system. Hereditary monarchy is supposed to be seamless but succession can be difficult – as it was when Edward VIII forsook the throne in favour of his mistress Wallis Simpson.

Coronations are crucial to monarchy. But they can go wrong. The oil used to anoint Elizabeth I was rancid and had an unhappy odour. James II found it hard to keep the crown on his head. Victoria's clergy were remarkably ineffectual and the Archbishop of Canterbury actually put the ring on the wrong finger of her hand. When Victoria withdrew to St Edward's Chapel after the anthem she was not amused to find the altar covered with sandwiches and bottles of wine.

Nonetheless most monarchs have found their coronation days to be remarkable moments of spiritual commitment if not transformation. Elizabeth I, despite the smelly salts, prayed thus "O Lord Almighty and everlasting God, I give Thee most hearty thanks that Thou hast been so merciful unto me as to spare me to behold this joyful day ... To Thee therefore, only, thanks, honour and praise, forever. Amen."

The future Lord Shaftesbury wrote that Queen Victoria's service was "so solemn, so deeply religious, so humbling, and yet so sublime! Every word of it is invaluable; throughout the Church is everything, secular greatness nothing."

After the unexpected coronation of King George VI and Queen Elizabeth, the new Queen wrote: "I was more moved & more helped than I could have believed possible ... Our great hope now is that as so many millions of people were impressed by the feeling of service and goodness that came from Westminster Abbey, that perhaps that day will result in strength and good feeling in individuals all over the world, & be a calming and strengthening influence on affairs in general."

When Queen Elizabeth II was crowned in 1953, she found, like her mother before her, an almost sacrificial quality at the heart of the service. She removed her crimson robe, her gloves, her jewels and her diadem and, clothed in a simple white linen dress over her satin gown, she was anointed.

It was the moment when the holy oil was applied to her, rather than her crowning with St Edward's crown of solid gold, that was of supreme importance for the Queen. Indeed it was the most solemn and important moment of her entire life.

The Archbishop of Canterbury said that her anointing "brought her into the presence of the living God". There is no doubt that she believed that then and has believed it ever since.

There has been much speculation about the present Prince of Wales's wishes for his coronation, much of it ill-informed. Will it be a multi-faith ceremony? Will he want to be Defender of Faith rather than of the Christian faith, as he once suggested?

Who knows? Perhaps he will want his coronation to be very different to all those four coronations in his family during the 20th century. But the Prince has a huge love for the history of Britain, for its language, its music, for Shakespeare, for Anglicanism, and a great feeling for the sacred. In fact he has often spoken of the need to retain a sense of the sacred in modern life. He believes that that "helps us to acknowledge that there are bounds of balance, order and harmony in the natural world which set limits to our ambitions and define the parameters of sustainable development.

Republican systems are, as I wrote above, perfectly sensible. But, unlike monarchy, they have no space for the sacred, the magical or the enchanted. They are not romantic. There is something astonishingly romantic, as well as devoted, in the way the Queen has kept faith with this changing island from the age of 25 to nearly 90 and, one hopes, beyond. She will pass on a unique and much loved system of government to her son and her other heirs.

Her achievement is astonishing and I believe it will be preserved. The end of the monarchy would mark another stage in the march of the state over almost every aspect of our lives. I do not believe we either need or want that.

This article was first published in a special commemorative edition of Newsweek magazine. To order your copy, write to emea-support@newsweek.com