On February 5, 1952, 60 years ago tomorrow, Elizabeth Windsor climbed a mgugu tree as a princess and the following morning came down as a queen. She and Prince Philip were in Kenya en route to Australia, staying at the famous Treetops Hotel. On February 6, she was watching the sun rise from a platform in the trees as an eagle soared above them - it was thought that, at that moment, her beloved father, George VI, died in his sleep at Sandringham.
A day later, the 25-year-old monarch arrived in London, dressed in black, and descended the stairs of her airplane to be greeted by the prime minister, Winston Churchill, who had served as a soldier in the reign of her great-great-grandmother, Victoria. Her youth and composure prompted hopes of a new era - not Victorian but a second Elizabethan Age. Interestingly, a tree featured in the accession of Elizabeth I, too. The first Elizabeth, also 25, sat beneath an oak at Hatfield, and when told she was queen, replied: "This is the Lord's doing, and it is marvellous in our eyes."
Elizabeth II had spoken from the heart four years before she succeeded, again in Africa, on her 21st birthday. "I declare before you all that my whole life, whether it be long or short, shall be devoted to your service and the service of our great imperial family to which we all belong." Six decades on, it is universally agreed that Elizabeth has been true to her word.
While she sounded so certain and determined, Elizabeth's destiny had only dawned in December 1936, when her uncle, Edward VIII, abdicated to marry Wallis Simpson, hoisting her hesitant, apprehensive father on to the throne. When a footman brought the news to the young princesses that their beloved papa was King, Margaret asked: "Does that mean you will have to be the next queen?" "Yes, someday," Elizabeth replied. "Poor you," countered Margaret. Some biographers claim that every night thereafter Elizabeth prayed for a brother.
That prayer was not answered, but she was able to marry, in 1947, Philip Mountbatten (born Prince Philip of Greece and Denmark), the man she had fallen in love with at 13. When asked what his job was, Philip has always answered "to support the Queen" and, for all his gaffes and restlessness, he too has been true to his word.
Despite the hopes, it was never to be a New Elizabethan Age. The fabric of Britain was still rent by the Second World War and as it recovered, Europe emerged and the Empire crumbled. But what arose from the remnants of the empire was the Commonwealth and its survival, against extraordinary odds, is one of the Queen's greatest achievements.
To keep that widespread family connected, she has travelled. In fact no one has travelled as far, so often and for so long - from her first trip abroad with her parents in 1947 to her most recent (no one would dare say last) to Australia in October last year. Abiding friends and allies are also remembered. Only weeks before their Australian trip, the Queen and Prince Philip visited Abu Dhabi. They had first come in 1979 - arriving on the Concorde and staying on the Britannia - and were welcomed by Sheikh Zayed. The nation was not quite seven; they visited the tallest building in the Middle East, Dubai's 39-storey World Trade Centre. In October 2011, 32 years later, they honoured their old friend at the Sheikh Zayed Grand Mosque. As one of the queen's biographers, Robert Hardman wrote, it was "a poignant reminder of how far she goes back in the memory of this young country".
Her longevity and constitution, reminiscent of her remarkable mother, continue to amaze. Elizabeth is not the longest-reigning current monarch - that honour belongs to Thailand's King Bhumibol, who ascended in 1946. History attributes the longest reign in living memory, of 82 years and 254 days, to Swaziland's King Sobhuza II (1899 - 1982). There is even one case, of Shapur II of Persia, whose 70-year reign (309-379) began in utero, when the crown was placed on his mother's belly. The British record-holder remains Queen Victoria, who reigned for 63 years and 216 days.
But neither Victoria - nor, in fact, the next three generations - had to suffer the spotlight of media intrusion - flashbulbs and paparazzi, hackers and harassment. Even today, the Thai king and, significantly, his family, are shielded by strict laws of lese-majesty. In recent decades the British royal family has enjoyed no such restraint and the press had a wild time in the 1990s as the marriages of three of the Queen's children failed under the unrelenting glare of commentators and cameras. This surely touched her personally but somehow the frailties and misfortunes of her children made their mother more faultless and majestic.
The only occasion where her unblemished record came in danger of being lost was the aftermath of the death of Diana in 1997. As hysterical Britons left bouquets by the thousand at royal residences throughout the kingdom (one paper dubbed it "floral fascism") the Queen remained remote at Balmoral. Her priority, she thought, was to her grandsons who had just lost their mother.
Her subjects thought otherwise and, inflamed by a baying press, with headlines imploring "MA'AM, SHOW US YOU CARE", they wanted their sovereign in London, grieving with them. At the urging of her courtiers and on the advice of her prime minister, she returned early to London, allowed the Union Jack to flutter at half-mast, and broadcast to her people. ("What I say to you now as your Queen and as a grandmother, I say from my heart.") All was well - the monarchy was saved and, as one royal watcher put it, "the Queen was back in charge".
The former Lord Chancellor, Lord Hailsham, once observed that while the US system of government was "an elective monarchy with a king who rules … but does not reign", the British system was "a republic with a hereditary life president who … reigns but does not rule". Another comparison is that of a non-executive chairman. The presence of a chairman guarantees balance. She may advise, recall past failures - and successes - represent the company at functions and listen to its problems.
If the Queen is the chairman, her chief executive is the prime minister. She has seen 12 of them. Her first, Churchill, born in 1874; her most recent, David Cameron, born in 1966, is two years younger than her youngest son.
Every week, the chief executive meets the chairman at her palace or castle, where discretion - on both sides - is absolute. Prime ministers, without the slightest fear of jealousy or betrayal, can unburden themselves and it is said they all came to look forward to these weekly encounters.
James Callaghan, prime minister in the 1970s, observed: "The Queen offers friendliness; not friendship." But what is discussed and what the Queen has thought of her successive prime ministers remains a mystery. There have been occasional leaks - that Edward Heath was cold and relations with Margaret Thatcher were frosty - but as no courtiers or secretaries are present, this can only be guessed at.
Her role is essentially a passive one. She does not criticise, lecture or dictate but she can and does question. It is said - again this is speculation - that when, in 1956, Anthony Eden told the Queen about the Government's intention to intervene over Suez, she apparently said: "Are you sure?". For Her Majesty, this is the equivalent of "Are you mad?".
The coolness, sagacity and restraint of Elizabeth II have been matched by her constancy and diligence - day in and day out, for six decades - a model constitutional monarch. It is impossible to imagine that this could be matched in this, or any other, century.
Mark McGinness is an Australian-born lawyer and writer working in Dubai. He is a regular contributor for The Times in London and the Fairfax Press in Australia as an obituarist.