By Georgina Littlejohn, 4 July 2012
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It was the holiday where she looked at her most relaxed and calm before it all ended in tragedy and her death.
It also cemented her relationship with millionaire playboy Dodi Fayed and yesterday, the actor playing the late film producer, made his first appearance in a new film about Princess Diana.
Canadian actor Cas Anvar was seen with Naomi Watts, who is playing the tragic royal, filming scenes for the movie, which was previously reported to be called 'Caught In Flight', but will go by the title of 'Diana'.
The pair were seen by a dock boarding a speedboat to take them to a yacht in scenes reminiscent of Diana and Dodi walking along a jetty in St Tropez in August 1997 to head back to their yacht.
This scene with Naomi shows her in a floral dress leaving a dinner date with Cas as Dodi, with world-famous celebrity photographer Jason Frazer hot on their heels.
In real life, he knew Diana well and was there on that last holiday of hers, but didn't go to Paris where she tragically lost her life a few days later.
Cas was in a linen suit as he helped Naomi board the speedboat, although the snaps of Diana and Dodi showed them dressed casually in the daytime.
The film will follow the last two years of Diana's life before her death and focus on her relationship with heart surgeon Dr Hasnat Khan who is being portrayed by Lost star Naveen Andrews.
But it will also look at her time with Dodi, who she was with at the time she died and the movie will include her death, aged 36, in a car in a Paris tunnel in 1997 with the Egyptian playboy.
And while Naomi, who was initially hesitant to take the role, has captured the Princess's grace, elegance and doe-eyed look, the producers have been careful, it would seem, not to completely imitate her wardrobe, with most costumes resembling those belonging to the late Princess.