Poor darlings, they have never had any fun yet,’ King George VI wrote in his diary shortly after the end of the war in 1945.

By ‘fun’, the King meant the kind of social life he had enjoyed in the 1920s, the non-stop dancing at lavish private balls or to hear Ambrose and his Orchestra at the Embassy Club in Mayfair.

Things had been very different for his daughters, the Princesses Elizabeth and Margaret, who spent their teenage years in more sombre circumstances, serving the Royal Family and the nation as Britain fought the threat of German occupation.

Perhaps for Elizabeth, this was no great hardship. Unlike her mother, who was the life and soul of parties, and in contrast to her sparkling younger sister, she did not enjoy big social gatherings.

At 19, Elizabeth would lie in the bath before dressing for a ball wondering what on earth she was going to talk about. She was not looking for the man of her dreams, after all. She had already found him and – just like her father when he fell for Lady Elizabeth Bowes-Lyon – she would consider no one else.

Elizabeth had just turned 13 when, in July 1939, she had a meeting with destiny in the form of a young naval cadet, Prince Philip of Greece.

She owed this encounter to the Prince’s Uncle Louis, born a Prince of Battenberg in 1900 but renamed Mountbatten and given the courtesy title Lord in 1917.

Lord Louis, as a great-grandchild of Queen Victoria, was her father’s cousin, always inexplicably known to family and friends as ‘Dickie’.

The decision that Philip should join the Royal Navy and not, as he had first chosen, the RAF, had been Mountbatten’s.

It would prove significant. When in July 1939 the King, the Queen and the two Princesses, accompanied by Mountbatten, made an official visit to the Royal Naval College at Dartmouth on the Royal Yacht Victoria and Albert, his nephew, Philip, was stationed there as a cadet

‘Philip accompanied us and dined on board,’ Mountbatten noted briefly in his diary on July 22, adding on the 23rd that: ‘Philip came back aboard V and A for tea and was a great success with the children.’

Aged 19, Philip was extremely handsome: tall, with Nordic good looks, bleached blond hair and fine features.

He was confident and, according to Marion Crawford, the Princesses’ governess, ‘rather off-hand in his manner’.

The crucial first meeting took place at the Captain’s House. Philip had joined the Princesses playing with a clockwork train on the nursery floor, but soon got bored with the childish amusement and suggested going to the tennis courts and jumping over the nets instead.

‘I thought he showed off a good deal,’ Crawfie wrote. ‘But the little girls were much impressed. Lilibet said, “How good he is, Crawfie. How high he can jump.” She never took her eyes off him the whole time.’

For his part, Philip was quite polite and paid Elizabeth no special attention, spending most of his time teasing ‘plump little Margaret’.

Elizabeth, however, had already fallen in love with her future husband – a fact that her father’s official biographer, Sir John Wheeler-Bennett, was authorised by her to confirm.

During the war, when Philip was serving in the Navy, Elizabeth and her friends used to joke about the Guards officers who protected her family, calling those they particularly liked their ‘flirts’. Yet she never forgot her meeting with the blond Prince, whose photograph she kept displayed prominently on her desk, his Viking features concealed behind a bushy beard which he acquired while posted to the Pacific.

Royal gossips had been connecting her name with Philip’s ever since their first encounter and, behind the scenes, his relations were already envisaging a sensational marriage for him, speculation that would continue during the war years.

Elizabeth was innocently unaware, although as early as September 1942 in a letter to Crawfie she dropped a hint that she had been discussing Philip with her friends and that he was ‘the one’.

In March 1944, the year of Elizabeth’s 18th birthday, King George of Greece (a cousin of her father) boldly raised the subject of an engagement with George VI, only to meet with a firm rebuff. ‘We both think she is far too young for that now,’ George VI told Queen Mary.

‘I like Philip. He is intelligent, has a good sense of humour and thinks about things in the right way… We are going to tell George that P. had better not think any more about it for the present.’

Undeterred, Mountbatten returned to the charge in August that year, suggesting that Prince Philip should change his Greek nationality for British citizenship as a first step. Having discussed the matter with George VI, Mountbatten flew to Cairo in August to put the idea to the Greek king.

Elizabeth’s father, however, remained cautious. ‘I have been thinking the matter over since our talk,’ the King wrote to Mountbatten, ‘and I have come to the conclusion that we are going too fast.’

Mountbatten, said the King, should confine his talks with George of Greece to the question of citizenship.

Even so, the romance continued to develop. Philip was often on leave in Britain during 1942 and 1943, staying with his cousin Marina at her house, Coppins, at Iver in Buckinghamshire, a convenient distance from Windsor.

In January 1944, Queen Mary confided to her close friend Lady Airlie that Elizabeth and Philip had ‘been in love for the past 18 months. In fact, longer I think… But the King and Queen feel that she is too young to be engaged yet. They want her to see more of the world before committing herself, and to meet more men. After all she’s only 19, and one is very impressionable at that age’.

Philip was 25 when he returned to England on March 20, 1946. As a handsome, experienced naval officer, he was intensely attractive to women. Apart from his physical appeal, he was good company. ‘He was very amusing, gay, full of life and energy and he was a tease,’ said one of his cousins. There had always been ‘armfuls of girls’ on his nights out ashore, according to his friend Mike Parker, but never, apparently, anything serious.

‘He’s 150 per cent male and that’s his trouble really,’ a contemporary said of him.

Philip was dominant, masculine, but not a romantic and was typically dismissive when later questioned by biographers about his courtship of Elizabeth, as if talking about such things was not what a real man would do. ‘During the war, if I was here I’d call in and have a meal. I once or twice spent Christmas at Windsor, because I’d nowhere particular to go. I thought not all that much about it, I think. We used to correspond occasionally…’ he said.

After the war, Philip was virtually homeless and practically penniless, with only his naval pay to live on. Whenever he had leave, he would dash to London and beg for a bed at the Mountbattens’ house in Chester Street, where the butler, John Dean, would wash and iron his shirts and mend his socks.

‘He was very easy to look after, and never asked for things like that to be done for him but I liked him so much that I did it anyway,’ wrote Dean.

He did notice that whenever Philip brought a weekend bag, it always contained a small photograph of Elizabeth in a battered leather frame.

Philip’s independence of spirit and his refusal to kow-tow to anyone were qualities that particularly appealed to Elizabeth, surrounded as she was by deference.

They were not, however, qualities which endeared him to courtiers. The Greek royal family was regarded as very much at the bottom of the royal heap – frequently without a job and, by royal standards, without means of supporting themselves.

Tommy Lascelles, private secretary to King George VI, probably summed up early Court reactions to Prince Philip when he told a friend: ‘They thought he was rough, ill-mannered, uneducated and would probably not be faithful.’ Elizabeth was unlikely to have been aware of the hostility, but even had she known it, such opposition would have made no difference.

She was in love and wanted to marry Philip, and when he proposed to her at Balmoral in the late summer of 1946, she accepted.

It does not seem to have been any formal kind of proposal. Prince Philip himself described it to his biographer in his usual offhand way: ‘I suppose one thing led to another. It was sort of fixed up. That’s what really happened.’

Nothing was to be official because the King wanted it that way. ‘Lilibet’s engagement keeps meandering on for ages,’ Margaret said to Crawfie.

Although George VI liked Philip and thought him a suitable husband for the Princess, it was with difficulty that he faced the wrench of parting from her and breaking up the family quartet – ‘us four’, as he called it – which was so close to his heart. When it came to finding a suitable husband for his daughter, however, the King’s options were limited.

In choosing Philip, who, despite his German blood was by nationality a Greek, one of Britain’s wartime allies, Elizabeth had, as usual, done the right thing.

Philip might have been poor, but he had a good war record, having been mentioned in dispatches for the battle of Cape Matapan, and he was royal, which meant he understood the constraints and responsibilities as no outsider ever really can.

Some of the more romantic-minded in Royal circles thought that if Elizabeth and Philip were in love, they should show it more. They were thought almost too keen to take part in all the social activities, never showing much tendency to be alone with each other. They shared the same attitude towards displays of emotion, regarding them as somehow ‘phoney’.

Elizabeth had always been emotionally aloof and undemonstrative, only, as Crawfie revealed, showing her feelings when deeply moved.

At a deep level, however, the couple understood each other. Her calm, controlled temperament was the perfect foil for his hyperactive, sometimes cantankerous nature; as was his penchant for positive action as opposed to her more conservative approach.

There were protracted discussions about Prince Philip’s naturalisation as a British subject and controversy as to what his new name would be.

The family name of the Danish royal house from which his father was descended, Schleswig-Holstein-Sonderburg-Glücksburg, was not only a mouthful but also sounded utterly foreign.

In the end, the Home Secretary, James Chuter Ede, suggested that the simple solution would be for him to take his mother’s name, Battenberg, for which the anglicised form of Mountbatten already existed.

The couple were married on November 20, 1947, at Westminster Abbey.

Just after the wedding, Prince Philip wrote to his new mother- in-law, Queen Elizabeth, saying: ‘Lilibet is the only “thing” in this world which is absolutely real to me and my ambition is to weld the two of us into a combined existence that will not only be able to withstand the shocks directed at us but will also have a positive influence for the good.’

Their affection for and loyalty to each other survived even the shock of Elizabeth’s accession to the throne at the age of 25, which simultaneously ended Philip’s enjoyment of a private, happy, married life and his hopes of a naval career.

The role of consort to a female sovereign has never been an easy one. But he would continue his unique support on that lonely plateau she shared with no one else but him.

As one of her principal private secretaries once said: ‘Prince Philip was the only man in the world who treated the Queen as a normal human being.

‘He was the only man who could.’