The fitting room at 5 Avenue Marceau, 1966

The fitting room at 5 Avenue Marceau, 1966. Yves Saint Laurent pins a black wool smoking jacket to the shoulders of a woman who has just walked off a plane from New York. She is not a model. She is a client, a friend, and — though neither of them would use the word — a collaborator. The jacket will appear in Vogue three weeks later. The woman wearing it will not be named.

This was how Saint Laurent worked. He designed for specific women, not archetypes. The house he built between 1961 and his retirement in 2002 was never about the abstraction of femininity. It was about three or four women at a time, each of whom gave him a way to think about what a garment could do. Some were famous. Some were not. All of them shaped the vocabulary he used to dress everyone else.

Three stand out. Not because they were the most photographed, but because they represent the three directions Saint Laurent pulled simultaneously: the intellectual, the performer, and the socialite who wanted to be taken seriously. Without them, the tuxedo jacket stays a novelty. The safari jacket remains workwear. The Mondrian dress is a museum piece, not a template.

Catherine Deneuve: the suit as armour

Deneuve met Saint Laurent in 1965, the year before Belle de Jour. She was twenty-one. He was twenty-eight. She needed a wardrobe for a film she had not yet shot. He needed a woman who could wear a man's jacket without performing androgyny.

The collaboration was not about seduction. Deneuve in Saint Laurent is controlled, remote, untouchable. The famous black wool Le Smoking she wore in 1966 — the first tuxedo jacket cut for a woman's body, with a narrower shoulder and a longer line through the torso — was not designed to make her look powerful. It was designed to let her be powerful without explaining herself. The jacket did the work. She stood still.

This is what Deneuve gave Saint Laurent: permission to make clothes that did not need a man in the room to make sense. The tuxedo jacket, the trench, the wide-leg trouser — these were not costumes. They were tools. Deneuve wore them the way a surgeon wears scrubs. The effect was not masculine. It was professional.

Saint Laurent dressed her for nearly forty years. The relationship was consistent, not dramatic. She wore his clothes to premieres, to dinners, to fittings for other films. She did not wear other designers. The loyalty was mutual. When he retired in 2002, she was in the front row. When he died in 2008, she spoke at the funeral. The speech was three minutes. She did not cry.

Betty Catroux: the customer who became the template

Catroux was never a muse in the traditional sense. She was a client who happened to look exactly like the women Saint Laurent wanted to dress. Tall, thin, dark-haired, American by birth, French by marriage. She bought her first Saint Laurent suit in 1967. She wore it with a man's shirt, no jewellery, and flat boots. Saint Laurent saw her at a party that winter and asked her to come to the atelier.

What followed was not a professional arrangement. Catroux became part of the house's internal logic. She attended fittings, offered opinions, and wore the clothes before they were photographed. She was not paid. She was not a model. She was the woman Saint Laurent used to check whether a sleeve worked, whether a hemline landed correctly, whether the proportion between jacket and trouser felt modern or fussy.

The influence shows up in the 1970s collections. The wide-shouldered blazer, the high-waisted trouser, the silk blouse worn open to the third button — these are Catroux's proportions, not a model's. Saint Laurent was designing for a woman who was five-foot-nine and weighed less than most of his fabric bolts. The clothes assumed height, narrowness, and a willingness to be looked at without flinching.

Catroux wore Saint Laurent until he stopped designing. She still does, though the house has changed hands twice. The archive pieces she owns — blazers from 1971, evening coats from 1983 — are not museum donations. She wears them to dinner.

Loulou de la Falaise: the collision of reference and irreverence

De la Falaise joined Saint Laurent in 1972 as a design assistant. She was twenty-four, Anglo-French, and had spent the previous three years making jewellery in a studio in London. She was not trained. She was not organised. She was, however, the only person in the atelier who could pull a reference from Diaghilev, Matisse, and a Marrakech souk in the same sentence and make it land.

Saint Laurent hired her to work on accessories. Within a year, she was sitting in on fabric selections, sketching embroidery patterns, and styling the runway shows. Her influence is harder to isolate than Deneuve's or Catroux's because it was not about silhouette. It was about the collision of high and low, the way a peasant blouse could sit next to a tailored jacket without either one losing authority.

The 1976 Ballets Russes collection — velvet knickers, brocade jackets, tasselled boots — was a de la Falaise production. So was the 1977 Opéra collection, which mixed eighteenth-century court dress with Moroccan caftans and came out looking like neither. These were not wearable collections in the way the Le Smoking was wearable. They were theatrical, referential, and unapologetically decorative. They were also the reason Saint Laurent never became a minimalist.

De la Falaise stayed with the house until Saint Laurent's retirement. She died in 2011. The jewellery she designed for the runway — oversized resin cuffs, gilt crosses, enamel hearts — is still referenced by the current design team. It turns up every few seasons, reissued or reinterpreted, because it solved a problem Saint Laurent never wanted to solve himself: how to make opulence feel accidental.

What they built

These three women were not interchangeable. Deneuve gave Saint Laurent structure. Catroux gave him proportion. De la Falaise gave him permission to be excessive. Together, they created the range the house still operates within: the tuxedo, the blouse, the evening coat that works over jeans.

Saint Laurent under Anthony Vaccarello has returned to this triad. The silhouette is Catroux. The attitude is Deneuve. The embellishment, when it appears, is de la Falaise. The women in the front row are different. The template is not.

A muse, in the end, is just a client the designer pays attention to. Saint Laurent paid attention to these three for forty years. The house has been paying attention ever since.