He had popped the question no fewer than three times when finally he met the woman he would marry.

After years of speculation over who would become his bride, Prince Charles announced his engagement on February 24, 1981.

His intended was, of course, Lady Diana Spencer, and the couple’s romance was seen as a fairytale – despite one awkward moment in their official interview which left his bride-to-be devastated and became seen as a portent of their eventual break-up.

The pair first met at shooting weekend at Lady Diana’s home of Althorp House, Northamptonshire, in November 1977, when Diana was just 16.

At the time Prince Charles was dating her older sister, Sarah, but later recalled: ‘I remember thinking what a jolly and amusing and attractive 16-year-old she was. I mean, great fun, and bouncy and full of life and everything.’

It wasn’t until 1980 that Charles made his move, two years after ending the relationship with Sarah.

In July 1980 Charles and Diana met again during a weekend at their friend Philip de Pass’s family home in Sussex. By September Diana was spotted at Balmoral.

After a whirlwind romance, in which the pair went on just a handful of dates, Prince Charles proposed to the then 19-year-old Diana in 1981 at a private dinner at Buckingham Palace.

They managed to keep the news a secret, but at 11am on February 24, it was revealed via a statement made by the Lord Chancellor.

‘It is with greatest pleasure that the Queen and the Duke of Edinburgh announce the betrothal of their beloved son the Prince of Wales to the Lady Diana Spencer, daughter of the Earl Spencer and the Honourable Mrs Shand Kydd,’ it read.

In their BBC engagement interview at the palace, Charles said that he was ‘delighted and frankly amazed’ that Diana was prepared to take him on, while Diana, shyly looking up through her blonde fringe, described her husband-to-be as ‘pretty amazing’.

When they were asked – at the Buckingham Palace photo call – whether they loved each other, Charles’s response to Diana’s ‘of course’ was the unforgettable: ‘Whatever in love means’.

In the moment, Diana somewhat awkwardly laughed off the jarring comment, which Charles compounded by adding: ‘”In love” is open to your own interpretation.’

Years later, however, she told her voice coach in a personal recording which appeared in the documentary Diana: In Her Own Words: ‘I thought, what a thick question. So I said, “Yes, of course, we are,” and Charles turned round and said, “Whatever love means”.

‘And that threw me completely. I thought, what a strange answer. It traumatised me.’

In the BBC interview, the Prince of Wales explained how, after he popped the question, he wanted to give Diana time to consider his offer, but she accepted right away and moved out of her apartment in Kensington to live in Clarence House up until the big day.

That day in February was the first time Diana, wearing a cobalt blue skirt-suit from Harrods, showed off her engagement ring to the world.

The stunning piece from Garrard was a 12-carat oval blue sapphire from Sri Lanka, encircled by a halo of diamonds and set in 18-carat white gold.

The ring was not a bespoke piece, but it had been inspired by the iconic brooch Prince Albert commissioned for Queen Victoria for their wedding day.

Today, Diana’s ring belongs to Catherine, the Princess of Wales, after Prince William used it to propose in Kenya in 2010, almost 30 years after his parents’ engagement.

On July 29, 1981, five months after announcing their engagement, Charles and Diana married in St Paul’s Cathedral in front of a global television audience of an extraordinary 750 million people.

Billed as the wedding of the century, it was a very different story behind the scenes. In the lead-up to the day, according to biographer Penny Junor, the true significance of Camilla had dawned on Diana.

‘Instead of explaining to Diana at the outset that Camilla was an old girlfriend, he had presented her as nothing more than a friend,’ she wrote in her book The Duchess: Camilla Parker Bowles and the Love Affair That Rocked The Crown. ‘He came clean after the engagement, admitting that Camilla had been one of his most intimate friends, but reassured Diana that from now on there would be no other women.’

Nonetheless, Diana felt so uncomfortable about Camilla’s presence in her future husband’s life, and about life in the palace, which she realised was stifling, that she tried to call off the wedding two days before it took place.

As Andrew Morton revealed in his bombshell 1992 book Diana – Her True Story, her sisters, Lady Sarah McCorquodale and Jane, Baroness Fellowes, dissuaded her from fleeing.

‘”Bad luck Duch,” they said, using their nickname for their younger sister,’ wrote Morton. ‘”Your face is on the tea-towels so you’re too late to chicken out now.”’

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Charles and Diana had two children, William and Harry, and remained officially married until 1996, when their divorce was finalised.

Their marriage was hit by infidelity on both sides, with Diana saying of Charles’ relationship with Camilla in her famous 1995 Panorama interview: ‘There were three of us in this marriage, so it was a bit crowded.’

In August 1997, just a year after their divorce, Diana died in a car crash in Paris.

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