Mystery of royal love letters burnt by the Queen's sister:  Princess Margaret had chauffeur destroy thousands of romantic Royal correspondence - including those from Diana 

To the few people on the beach, it was just another small figure swimming in the warm Caribbean. But to the Queen, in a one-piece swimsuit and doing the neat breaststroke she first learned half a century earlier at the Bath Club in Mayfair when she was nine, it was the kind of escape she hadn’t known for decades.

The Queen had dropped in to see her sister Margaret at her beautiful, beachside house, Les Jolies Eaux, on Mustique, the exclusive holiday island developed by Colin Tennant, later Lord Glenconner.

She had arrived on the royal yacht Britannia and brought Prince Philip as well as her swimsuit. As Glenconner’s widow Lady Anne, a train-bearer to the Queen at her Coronation as well as a lady-in-waiting to Princess Margaret, reveals: ‘The Queen normally doesn’t swim in the sea.’

Living the life: Princess Margaret, pictured, was well known for her hedonistic lifestyle and a string of lovers

Indeed, she doesn’t swim in public because she doesn’t want to be photographed. ‘Luckily with Mustique we had full control so no photographers were there,’ says Lady Anne, 83, whose father, the 5th Earl of Leicester, was equerry to the Queen’s father before he became King. ‘She enjoyed it very much.’

It was the second time the Queen had called on her sister at the house she built on a choice piece of land that Colin Tennant gave Margaret as a belated wedding present after she married raffish society photographer Antony Armstrong-Jones, now Earl of Snowdon.

For the Queen it was a fleeting taste of the sybaritic high life and relative freedom that were the hallmark of Margaret’s existence. 

Such freedom had been all but lost to the elder Lilibet on the abdication of her uncle King Edward VIII. Fleeting is an understatement — on each occasion she was there for just a day and stayed on the royal yacht.

But there was just time enough to watch the sand sharks coming in to give birth in the shallow bay by rubbing their stomachs against the sand.

Another spectacle, specially laid on for the Queen’s arrival, was the sight of villagers decked out in clothes hastily bought at a jumble sale, all lined up to greet her.

The Queen took one look and waspishly declared to her sister: ‘Margaret, I had no idea Mustique was in a Victorian timewarp.’

All those years ago, when they first learned their own father, the shy and stammering Bertie, was unexpectedly going to be king, Margaret, six, asked her ten-year-old sister if this meant she would be Queen one day.Lilibet replied: ‘Yes, I suppose it does.’‘Poor you,’ said the younger sister.

Pictured, Princess Margaret talks to a friend on a beach in Mustique, in the West Indies, in 1976 

So much sooner than anyone expected, a mere 16 years later, there was Lilibet being anointed and crowned, with Prince Philip, as Lady Anne remembers, being ‘sooooooo good looking’ and the Archbishop of Canterbury, Dr Geoffrey Fisher, who moments earlier had placed the St Edward’s Crown on the Queen’s head, producing a bottle of brandy and inquiring: ‘Anybody like a sip?’

Anne Glenconner also remembers how ‘very sad’ Princess Margaret, 22, was looking. ‘I said to her: ‘Ma’am, you look so sad,’ and she replied: ‘Of course I feel sad, I’ve lost my beloved father and, in a way, my sister because she’s going to be so busy now.’

That did not turn out to be true. Until Margaret’s death six weeks before the Queen Mother’s in 2002, she and the Queen shared intimacies much as they did when they were children. But Mustique was something they could never really share.

The house was eventually inherited by her woodworker son Viscount Linley, who promptly sold it.

There is a different family tie to the island now — Carole and Michael Middleton holiday there with their children and, in recent times, also with William and Kate.

But Les Jolies Eaux, and that brief swim in the gently lapping pale blue water, will always symbolise the difference between the sisters’ lives.

As the Queen’s lifelong friend and cousin Margaret Rhodes, 90, says: ‘She’s never been able to holiday like other people, to be a tourist going off to see the sights of Paris.

‘In all the years she has been Queen she has never had a proper foreign holiday or been able to say: “Oh, it’s a lovely day, let’s go somewhere and take a picnic.” ’

Janey Stevens, Princess Margaret’s lady-in-waiting for more than 30 years, remembers how, when they were away, they ‘always looked for presents’ for Margaret to take back for the Queen.

Elizabeth envied her sister for her countless glamorous excursions, especially the one in 1959 when Margaret, still single, went on holiday to Rome with the Queen Mother, taking in all the sights accompanied by the British ambassador before flying off to Paris to do the same there.

Nevertheless, the feeling remains that Margaret’s life was one that would never have suited her older sister. They were always very different little girls. 

‘Elizabeth was never as ebullient as her sister,’ says Mrs Rhodes. ‘She was always more serious, though she was fun as well.’ With a twinkle she adds: ‘It was very clever of the Almighty to get the right one first.’

 As children, Elizabeth, older by four years, was very motherly towards Margaret, often telling her to behave. Pictured, the princesses (Elizabeth left and Margaret right) with The Queen Mother and King George

As children, Elizabeth, older by four years, was very motherly towards Margaret, often telling her to behave — for example, not to point at someone wearing a funny hat.

But, typical siblings, they sometimes fought. Marion Crawford (Crawfie) their nanny, recalled Margaret biting on occasions, while Lilibet ‘was quick with her left hook’. Surprisingly, perhaps, Lilibet was the one with the quicker temper. She also took longer to recover after a set-to, and always had more dignity.

One consequence of Lilibet becoming the heir to the throne was the additional education thrust on her, particularly about constitutional history, with tutors from Oxford, Cambridge and Eton, none of which was offered to Margaret.

Says Anne Glenconner: ‘She was sort-of left with the French governess and Crawfie, the nanny.’

In later years, adds Lady Anne, the Princess would sometimes lament: ‘I wish I’d been educated like my sister.’

This resentment at being excluded may well have been why, as an adult, Margaret had what Lady Anne describes as a ‘slightly sparring relationship’ with her mother’ — very different from the one that the Queen had with her.

This was exacerbated by Margaret having to move, with her mother, out of Buckingham Palace after the accession and into the much smaller Clarence House. 

The Queen was happy in Clarence House but Winston Churchill, then Prime Minister, insisted the monarch had to live in Buckingham Palace.

‘I do think Princess Margaret had a more difficult time because the Queen had married and gone off and had children and Princess Margaret, a grown-up daughter, was still living with her mother,’ adds Lady Anne.

The Royal Family, including a young Prince Charles, second left in the back row,  pose for an official photo at the wedding of Princess Margaret to photographer Antony Armstrong-Jones, in 1960 

This didn’t break the sisterly bond. What nearly did was the wilful Margaret falling in love with Group Captain Peter Townsend, a father of two sons, whom she had known since the age of 14 when he arrived at Buckingham Palace as equerry to her father.

Several years into their affair, Townsend and his wife Rosemary were divorced. Then Margaret reached 25, the age at which, under the Royal Marriages Act, she no longer needed the Queen’s consent to marry.

She could now choose for herself between renouncing her rights to the throne, giving up the gilded entitlements of an HRH, and her love for the charming and good-looking Battle of Britain fighter ace.

The huge constitutional crisis that blew up over the possibility of the Queen’s sister marrying a divorcee would, in later years, look almost comical as the marriages of the Queen’s own children were falling like ninepins.

But, then, in the Fifties, attitudes were different.

In the end, Margaret chose the royal life. Many thought she did so because she was frightened of a future outside the privileged royal circle.

But Anne Glenconner, her lady-in-waiting for 34 years, says the Princess did it out of religious principle and loyalty to the Queen.

As she recalls: ‘She said to me: “Anne, people say all sorts of things [about why she gave up Townsend]. Well, actually it was my religion. I was brought up to be against [divorce] and my sister is the head of the Church and I just couldn’t do it.” ’

Princess Margaret, known for her beauty and glamorous lifestyle, almost broke her strong sisterly bond with the Queen when she embarked on an affair with a married man

As things turned out, Margaret’s subsequent marriage to Lord Snowdon was the first of the Queen’s immediate family to end in divorce in 1978. This did not, however, change her feelings.

‘Princess Margaret was a very religious person and didn’t like the idea of divorce at all,’ says Lady Anne.

‘And it made her desperately sad for her sister when her children’s marriages ended in divorce because she loved and admired the Queen so very much.’

But as Margaret’s freedom drew her into showbusiness circles and an edgy bohemian set, reports of her amours — including nightclub pianist Robin Douglas-Home, who committed suicide after she left him for film star Peter Sellers — concerned the then Prime Minister Harold Wilson enough for him to raise them with the Queen’s private secretary Lord Charteris.

True, the Queen had once remarked, tongue-in-cheek, to Charteris that Margaret was ‘living in the gutter again’, but she never really worried about the activities of her younger sister because they had always been totally loyal to each other. 

She knew Margaret would never do anything outrageous enough to seriously embarrass her.

Besides, says a guards officer friend of Margaret: ‘The Queen was always able to handle her sister, and with much greater skill than she handled her children.

' If Margaret didn’t want to do something the Queen would smilingly say: “Oh, all right,” as if saying: “You won’t be missed.” That usually brought her to heel.’

The Princess’s later lengthy relationship with the much younger Roddy Llewellyn, who subsequently married a woman his own age, simply became part of the social scenery.

Throughout all these years, Margaret continued to be the most intimate confidante of her own generation to whom the Queen turned when she wanted to talk. They telephoned each other every day.

The Princess’s divorce made her a useful, and calming, sounding board when the Queen needed to talk to someone about the marital problems of her children.

But there is one intriguing occasion, when Margaret seems to have taken matters into her own hand.

She went to Clarence House to see the aged Queen Mother and took away a large bag of letters. She handed them to her chauffeur of 26 years, David Griffin, and instructed him to burn them.

Supervised by the Princess, who wore yellow rubber gloves, he set fire to them in a dustbin in the garage at Kensington Palace where Margaret had apartment 1A now occupied by William and Kate.

‘The smoke was so thick it made her eyes water and she had to leave,’ recalls Griffin.

‘We went back to Clarence House several times over a period after that to collect more letters and papers, and burned them all. 

'I saw Diana’s name on a few, and even her crest and her handwriting, and there were lots of others addressed to the King and Queen, so they were quite old.

‘The Princess never said why she was doing it, but she was very determined that they should all be destroyed, thousands of them. I remember thinking we were putting a match to history.’ 

Fire: Princess Margaret's chauffeur of 26 years, David Griffin, said that she, pictured with the Queen and a young Prince William and Prince Harry, instructed him to burn thousands of letters

One theory among courtiers is that the Princess was destroying letters that related to both her nephew Charles’s marriage and her own tangled private life to prevent them falling into the hands of the royal archive on her mother’s death.

An incident that will not be in the archive involved a very different kind of crisis. The Queen had gone for a walk in the Buckingham Palace gardens, and Margaret had turned up to have her regular afternoon swim in the Palace pool, when there was a sudden security emergency.

An intruder was thought to have climbed the Palace walls, and when the Queen returned from her walk she found her way back in to the building barred by a police officer who told her: ‘I’m sorry, your Majesty, but I can’t let you in as there might be an intruder inside.’

What happened next was witnessed by chauffeur Griffin. ‘The Queen went ballistic,’ he says, ‘and just then the Princess arrived from the pool. The Queen shouted: “Margaret, they won’t let me in to my own house.”

‘The Princess calmed her down, and her own bodyguard said to the Queen: “Don’t worry, your Majesty, if I see him I’ll shoot him.” It only lasted another moment or two, and then they went in for tea. It was the only time I ever remember the Queen losing her temper.’

When Griffin drove the Princess to the Tower of London, to join the Queen and some friends whom she had taken for a picnic, and to witness the ancient Ceremony of the Keys, it was a much more light-hearted affair.

The keys to the Tower are produced at the end of the day, and marked by the booming Beefeters’ demand: ‘Whose keys are these?’ Comes the response: ‘Queen Elizabeth’s keys.’

Watching with her sister and friends nearby, the Queen gleefully couldn’t resist miming: ‘My keys, they’re my keys,’ while pointing at herself.

What is clear is that Princess Margaret’s fears on the day the Queen was crowned, that her enthronement would come between them, were never realised. 

The sisters remained as close as ever. Only when the Princess had the first of a series of strokes, and then, in the most ghastly possibly bathroom accident, scalded both her feet, did events come between their daily chats.

After the first stroke in 1998, the Queen personally took charge of her welfare and called her constantly to see how she was progressing. 

Mr Griffin said that while he was burning the letters he noticed that some were from Princess Diana, pictured with Princess Margaret in 198

Mustique, of which the Queen had such brief but happy memories, became part of the convalescence. A year later, it also became part of the nightmare.

Here was the one place where the formalities of royal life were largely put on one side. Princess Margaret even drew her own baths. Says her long-time lady-in-waiting Janey Stevens, 78, who was in Mustique with her: ‘She always had very hot water but this time she forgot to put in any cold. It was dreadful. She put her foot in the bath and it stuck to the bottom.

‘Then she put her other foot in to try and free herself, and it got stuck too. She fell out of the bath and onto the floor, which is where I found her.’

The Queen, highly distressed, was in constant touch with Margaret, whose burns made it impossible for her to walk and was unable to fly home for several weeks.

As Lady Anne Glenconnor, who was also there, recalls: ‘When the doctor felt she could travel, she sort of didn’t want to go. It was the Queen who encouraged her to return to Britain, telephoning her and saying: “Margaret, you should come back.” ’

It was arranged for the Princess to fly home on Concorde. But, to the Queen’s sadness, despite personally organising a specially-adapted car for Margaret which could accommodate her wheelchair, her sister was never the same again.

Margaret died in February 2002. She was 71. Six weeks later the Queen Mother died. Almost at a stroke, the Queen had lost her two ‘best friends’.

It had the effect of bringing her closer than ever to her daughter Anne, and also to Prince Edward’s wife, Sophie.

Margaret’s death, after four years of suffering, also brought the Queen particularly close to her sister’s children, David (Viscount Linley) and Lady Sarah Chatto, an artist, both among the Queen’s favourites of all the younger generation in the Royal Family.

The irony is not lost on the Queen that while she and Philip have a strong marriage but three divorces among their children, Margaret had a tumultuous marriage that ended in divorce, yet the marriages of both her children are strong.

Linley’s wife is the former Lady Serena Stanhope, daughter of the Earl of Harrington, and Lady Sarah is married to artist and former actor Daniel Chatto. Each has two children.

The Queen’s closeness to Princess Margaret’s daughter can be measured in where her thoughts went at a Palm Sunday service in the Royal Chapel at Windsor when she was offered the traditional palm cross by the vicar, Canon John Ovenden.

‘Would you mind if I have two more?’ she asked her vicar. She wanted them for Lady Sarah’s children.

Three or four times a year the Queen goes alone to stay at Craigowan Lodge, a stone-built house on the Balmoral estate a mile from the castle.

She goes into this semi-retreat (although those red boxes of Government papers always follow her) to write personal letters, to read and to walk.

Her next visit to Craigowan will be later this month, just before Easter. Only one family member ever accompanies her there, and that is Lady Sarah, 51.

Friends say it keeps the Queen close to the sister who — for all her occasional waywardness — she adored.

Additional reporting: Emine Sinmaz and Beth Hale