It was at Highgrove, on July 18, 1997, where Prince Charles hosted a £30,000 party for Camilla Parker Bowles to celebrate his future Queen’s 50th birthday.

The glitzy celebration and Camilla’s birthday a day earlier would have been lapped up the by the Press – if a mischievous Princess Diana had not been determined to knock her erstwhile rival off the front pages.

Guests such as novelist Jilly Cooper and broadcaster Melvyn Bragg sipped champagne on the lawn as a clarinettist played jazz music, before they enjoyed a five-course dinner in the lavish 120ft marquee.

But Diana became the centre of attention by making a splash in the Mediterranean, where she was holidaying with her sons, Princes William and Harry.

Wearing a leopard print swimsuit, the Princess, who was staying with boyfriend Dodi Al Fayed at his father’s villa in the south of France, was snapped by the paparazzi as she purposely frolicked in the sea, on July 17, 1997.

So, when Camilla woke up the following morning, on the day of her party, she was greeted with the headline: ‘Dear Camilla. This will keep you off the front page. Happy Birthday & Breast Wishes. Love Diana.’

On July 17, 1997, the 50th birthday of Camilla Parker Bowles, Princess Diana was photographed wearing a leopard print swimsuit as she holidayed with boyfriend Dodi Al Fayed at his father’s villa in the south of France

The day after Diana’s swimsuit appearance, Camilla Parker Bowles enjoyed the lavish £30,000 party put on for her by Prince Charles at Highgrove. Above: Camilla arriving for the celebration accompanied by her sister’s husband, Simon Elliot, July 18, 1997

Princess Diana was joined on her holiday in France by her children, Princes William and Harry (above)

Diana’s salvo was the latest in the battle between the divorced Diana and her ex-husband, dubbed the War of the Wales.

It was destined to be one of her final public appearances: just six weeks later she and Dodi were killed in a car crash in Paris.

But the photographs of her in a series of stunning Gottex swimsuits have endured.

Costume designers Amy Roberts and Sidonie Roberts went as far as asking the swimwear brand to recreate them for actress Elizabeth Debicki to wear in the Netflix hit The Crown.

‘We thought: “Why don’t we just go to them and see?’,” Sidonie said recently.

‘They were brilliant and made them for us. We had fittings so that Elizabeth felt comfortable as well.’

It is not known where Diana bought the swimsuits. The late Queen’s corsetiere June Kenton, who was a friend of the Princess, claimed in her book Storm In A D Cup that Diana had bought them from her shop Rigby & Peller.

‘Diana had an amazing figure,’ she wrote. ‘She ordered a few swimsuits by Gottex, the Israeli designer, and some cover-ups and beach bags to match.

‘I recognised the swimsuits in photos of her on that last fateful yachting trip with Dodi Fayed.’

But, last summer, in the run-up to the final series of The Crown, Gottex claimed on Instagram: ‘The Diana suit was made especially for her after a meeting between the Princess and Mrs Lea Gottlieb, the first lady of Israeli fashion and the founder of Gottex.’

Either way, the extraordinary story of the Jewish designer, who was dubbed the ‘Queen of Israeli fashion’, must have resonated with Diana, known as the ‘Queen of Hearts’.

Mohammed Al Fayed’s home in St Tropez, where Diana and the boys stayed in July 1997

Elizabeth Debicki’s costume designers from The Crown visited Gottex and they recreated the swimsuits for the Netflix show

The marquee set up at Highgrove for Camilla’s 50th birthday party

Not only did she and her husband Armin, who spent the Second World War in a labour camp, survive the war, but they built a multi-national company after selling her wedding ring to raise money and borrowing a sewing machine.

Born in Sajószentpéter, in Hungary, in 1918, Mrs Gottlieb was raised by an impoverished aunt.

Her plans to study chemistry at university in Budapest were thwarted by quotas imposed on Jews studying at academic institutions.

Instead, she worked as a bookkeeper at a raincoat factory, where she met her husband, who was running the family firm. They had two daughters, Miriam and Judith.

But when Hungary was occupied by the Wehrmacht in 1944, Armin was shipped to a labour camp and she and their daughters had to survive the war alone.

Switching between Sajószentpéter and Budapest, she hid her head in bouquets of flowers at checkpoints to evade being recognised. At one point, spotting a Nazi with a pistol, she and her children hid in a pit.

The late Queen’s corsetiere June Kenton, who was a friend of the Princess, claimed in her book Storm In A D Cup that Diana had bought the Gottext swimsuits from her shop Rigby & Peller

Last summer, in the run-up to the final series of The Crown, Gottex claimed on Instagram: ‘The Diana suit was made especially for her after a meeting between the Princess and Mrs Lea Gottlieb, the first lady of Israeli fashion and the founder of Gottex’. Above: Lea Gottlieb during a New York fashion show in 1988

After surviving the war, the family emigrated to Haifa, in Israel, in 1949. She later recalled: ‘We came with nothing, without money, with nowhere to live. The first two or three years were very, very hard.’

Borrowing money from family and friends, the couple opened a raincoat factory in Jaffa but switched to swimwear when they ‘saw no rain, only sunshine’.

She took her inspiration from the land – ‘the turquoise of the Mediterranean, the golden yellow of the desert sand, the blue of the Sea of Galilee, the pink of Jerusalem stone, and the many shades of green of the Galilee’.

By the time Diana wore her swimsuits, the company had a $60 million turnover and had dressed everyone from Queen Sofia of Spain and Elizabeth Taylor to Brooke Shields and Nancy Kissinger.

When she died at her home in Tel Aviv, in 2012, at the age of 94, the Center for Israeli Education, in her adopted country, described her as the ‘Queen of Israeli fashion’. A title well deserved.