‘We are taking the picture to Cannes,’ said John Gore, the producer and financier of My Duchess, my new film about the Duchess of Windsor. ‘How exciting!’ I said. Then, a minute later, I thought, ‘Oh God! What am I going to wear on the red carpet?’ The following day I told my artist friend David Downton about my dilemma while lunching at Claridge’s. ‘Let’s call Stéphane Rolland,’ he said. ‘Wonderful idea!’ I said. ‘He’s great! He made the red dress I wore for the Heart Truth Red Dress gala in New York a few years ago, and it was spectacular.’

David called Stéphane as we had coffee, and the talented couturier sketched a terrific drawing of a beautiful white dress with ruffles while they chatted, and texted it to David. ‘Amazing!’ I exclaimed. It was perfect – exactly what I would have wanted. He must have read my mind, and it took all of five minutes. Three weeks later, Stéphane and his long-time collaborator Philippe Delessard arrived at my apartment with a massive suitcase containing a gorgeous dress that fitted me perfectly.

My dresser, Chrissy, and I went through my entire wardrobe trying to find suitable outfits for the three days we were to spend in Cannes. I had to prepare for two dinners that were supposedly casual (difficult as I can only do casual when I exercise) and a lunch with press followed by a photo shoot with Isabella Rossellini, and finally another outfit to appear on stage to introduce the screening. It took Chrissy and me all day to collate the right outfits, shoes, bags, jewellery, etc. I don’t have a stylist on speed dial, but luckily I have lots of clothes. I practised dance steps and balance with my friend the choreographer Paul Robinson. God forbid I should slip on the red carpet steps. I watched some reels of actresses at previous Cannes red carpets and all I could say is: I had better watch out.