'It is important to have Loulou beside me when I work on a collection.' he told Axel Madsen, in 1979. 'I can't explain her job . . . it has to do with her manner, her straightforwardness,' To translate: Loulou de la Falaise Klossowski comes in somewhere before the scissors are added. For 20 years she has been the walking colour- card, the inspiration for all those 'folkloric' collections based on Russian cossacks and Chinese empresses, the back-stage manager, the sounding board for ideas and the chief confidante of Yves Saint Laurent.
She also designs the YSL jewellery, and for the first time will be credited for doing so at next month's couture show in Paris. Though the pieces won't bear her name - 'Imagine, I'd always have to make such huge jewels to get it all on]' - she will be noted in the programme.
In any other couture house, there would be nothing unusual in this. But one of the enduring myths of Saint Laurent has been that he did everything himself. That is, until last July, when Robert Merloz, the designer of the YSL fur line and protege of the company money man Pierre Berge, launched his own collection under the YSL umbrella. The show went down like a rock. But it was significant; it was the company's first public admission that there was more creative input than just Yves at 5 Avenue Marceau.
Few people in the fashion world will be surprised at the 'revelation'. Saint Laurent aficionados have known for years that Loulou was behind the jewellery, and in any case, the pieces themselves let the cat out of the bag. Necklaces strung with shards of jet; amulets of blue glass on black, like ice on a crag; chokers of what look like pale pebbles bashed smooth on a blustery Breton beach, all have the froideur, the cool brittleness of Loulou de la Falaise. And the sheaths of bracken, dip-dyed gold and clustered with garnet berries, the huge collars of blood-red jewels, and next season's gilded Chinoiserie, all share her very distinctive grandeur.
Meeting Loulou is always unnerving. She is friendly enough, but her scornful gaze makes her critical in spite of herself. Rake-thin, resolutely chic and feline-faced, she looks like the cat that turned its nose up at the cream. And even in a cropped, fluffy purple sweater, she emanates elegance. She talks in the slow, rusty way of the bilingual speaker (she is half French, half English) whose turns of phrase are not quite up to date, and uses quaint terms like 'jolly' and strange expressions to describe life at YSL: 'we are used to our own soup'.
She first met Yves at a party in 1968, when she thought the promised introduction to 'Yves and Pierre' meant she would get to meet Pierre Cardin. At that point, despite being fashion editor of Queen in London ('I was busy earning my living while someone in the office popped pills and someone else screamed'), she hadn't heard of the designer who is credited with turning Paris fashion upside down: 'We had Mary Quant, Carnaby Street, Ossie Clark . . . It is only now that people say Yves caused an international sensation,' she remembers, 'We thought France was stuffy, although I did think a pair of thigh-high lace-up boots which turned out to be his were rather nice.'
In 1971, a YSL collection inspired by the Forties, including a cropped emerald-green fox fur coat, was panned as a hideous parade of street hookers. The clothes didn't sell, and found their way instead as boxed gifts to Loulou, whom Yves had been very taken with. By this time she was in New York, hanging out with the models Veruschka and Pat Cleveland, the illustrator Antonio Lopez, and the designer Halston, in whose all-white West 55th Street apartment the smart set congregated. By 1972, she was in Paris, 'where Yves didn't tell anyone he had hired me, and I didn't know what he had hired me as. But back then,' she says, 'we were all friends. Fashion wasn't run by businessmen who kick a designer out and put in a robot instead. It wasn't traumatic then. One just did one's thing.' And in Loulou's case, one's thing was to be chic.
Today, this is harder, particularly as whatever 'thing' it is that Yves Saint Laurent is doing is done behind closed doors, which aggravates the media-crazed fashion world no end. Loulou snaps at the suggestion that she covers for him. 'Yves is very accessible here. It is the contrary to what people assume,' she insists. 'And if he wants to be elusive, then I don't want to be the front- person. I shouldn't have to talk for him. It's ghostly. It is exaggerated, this myth. He's just hard at work, and when it is over, we both crawl home.'
For all that, Loulou de la Falaise has lived more than most people dare dream about - and her family history is the stuff of blockbuster novels. Indeed her mother, Maxime de la Falaise McKendry, still awesomely elegant, is currently engaged in writing it all down.
Loulou's mother, nee Maxime Birley, daughter of the celebrated Irish beauty Rhoda Birley and the society painter, Sir Oswald Birley, of the family behind the ritzy Annabel's and Mark's Club, married Comte Alain de la Falaise in New York just after the war. His brother, Henri, Marquis de la Falaise, had already caused a stir by marrying Gloria Swanson, who immediately demanded she be called 'Marquise' and appointed liveried footmen to her Hollywood mansion. Henri later married the actress, Constance Bennett, while another member of the family, the black sheep, shot himself over gambling debts.
Meanwhile, Maxime was transformed under her married name and lived in Paris, where Loulou and her brother, Alexis, were born. The marriage lasted until Loulou was three. Maxime went on to work for Schiaparelli and Paquin.
Alexis married Louisa Ogilvy, passing the de la Falaise beauty through the blood lines. His daughter, Lucie, is now the face of Yves Saint Laurent fragrance and, this month, made it on to the cover of American Vogue. His son Daniel is an actor, who appears on intimate terms with Madonna in the 'Erotica' video. Loulou's daughter Anna Baladine Rose Cassimira Klossowki is, at seven, already demonstrating that style is in her blood. 'She and her best friend cry in sympathy if one of them has to wear the wrong-shaped trouser,' reveals her mother.
'I hated clothes as a child. I thought skirts were pathetic,' Loulou says, ' but then I stuck with my brother. We felt very abandoned, so we were close in everything we did.' Loulou was shunted around boarding schools in England, the French Lycee in New York, and finishing school in Gstaad, from which she was unceremoniously expelled because her St Bernard ate a poodle.
'In fact I was booted out for various reasons. We weren't allowed to keep pets, but I hadn't had the dog very long at all. I saw the dog carrying such a heavy milk pail it was leaving blood marks in the snow, so I rescued it, washed it, bought it a huge collar and walked down the street. There was this little cafe-au-lait poodle and it just went for it. It was icy, so I just skidded along behind as it chewed it up. I also got accused of stealing Liz Taylor's Afghan hound, but in fact it adopted me, so that was rather unfair.'
Disgraced and home in England, she was supposed to have 'come out', but her grandmother neglected to put the necessary mention in the Times. She found her first husband pretty quickly anyway, and married Desmond FitzGerald, the Knight of Glin, at 18. She spent a while dressing up regally, entertaining royally and playing chatelaine of an Irish castle, until boredom set in. They parted without bitterness. Her mother, who has since said she thought Loulou had more in common with the tinkers, was not surprised.
Her destiny was to become an 'It' girl. She roomed with one of Schiaparelli's granddaughters, Berry, of the celebrated pair Marisa and
Berry Berenson, in New York, and hung out. Chiffon-thin, with flame red hair, she modelled for a while, 'nothing official, just chums spending all night doing a fitting in return for being taken out to dinner'. Christmas was spent at Mick and Bianca's, with John and Yoko, and Andy Warhol. And then came the invitation from Yves.
Soon she was in Paris. When she married again, to Thadee Klossowski, son of the painter Balthus, Yves gave them a wedding party in the Bois de Boulogne where two thousand guests were boated across a lake to a lavishly decorated island. Loulou became famous for her parties: before Anna was born, she was fast becoming a legendary hostess in the manner of Nancy Cunard and Daisy Fellows. At one fancy-dress party, where Saint Laurent came as himself, she came as a fallen angel and her husband as an 'angelic' one. At another, she turned up as a walking tree, armed with secateurs, so fellow party-goers could prune her where it scratched. It was, she says, agony, 'but fun'.
The French expression 'Il faut suffrir pour etre belle' could have been coined for Loulou de la Falaise. The jewellery she designs can bow the head with its colossal weight. The earrings, while magnificent, tug on the lobes. Some of the pieces are so heavy, you need a neck brace to carry them off. Loulou, of course, puts the lot on her tiny frame and holds her head high.
So should one suffer to be beautiful? 'Well, yes, I suppose. It doesn't mean that one should have to wear corsets, but if you have got a headache, it is not very attractive to complain about it,' Loulou says. 'If you have decided to go out you have to put your best foot forward and keep yourself up. Otherwise, one may as well wear a track suit.' And does she, ever? 'Never, I disapprove of too much comfort.'