Jane Birkin, the British singer and actor who made Paris her home, carried a straw basket so often that it inspired a very famous handbag. Photos from her youth show slouchy knits, button-downs, jeans and smart little shoes, all worn with total ease. Muuñ's woven straw Sophie basket, Lauren Manoogian's ivory long-sleeve pima tee, Alix of Bohemia's off-white fringed open-knit mini dress and Chloé's gold round sunglasses set the tone.

This is the Birkin formula at its purest. Maria McManus's light blue organic poplin shirt, worn open at the collar, goes with Frame's dark low-rise Rodeo flares, and Jimmy Choo's black leather Margot ballet flats keep the look low to the ground. St. Agni's large brown woven leather tote is the grown-up version of her basket.

Her wardrobe leaned on short hems and plain knits, a pairing that still looks fresh. &Daughter's yellow wool Innes V-neck sweater and Arma's chocolate suede Melody mini skirt make that easy, and The Row's black velvet Ponti slippers add some polish. Savette's black woven raffia Symmetry bag keeps a nod to the basket.

The seventies version of the formula swaps the flare for a bootcut and adds a belt. The Row's dark brown braided Fisherman belt threads through Khaite's dark Conforti bootcut jeans, with Agolde's white ribbed Leigh tank on top. Saint Laurent's brown suede Francoise knee boots bring the heel and the decade.

A trench over jeans is a very French way to get dressed, which suits a British woman who spent most of her life in France. Ossou's brown cotton-twill Delta trench goes over La Ligne's cobalt striped knit shirt with its white collar, and Mother's dark straight Kick It jeans keep it relaxed. Herbert Levine's black Pump Du Jour kitten heels stand in for the smart little shoes that turn up in so many photos of her.

Birkin's style lasts because it was never really about the clothes, which were mostly jeans, shirts and sweaters. If you take one thing away, let it be that her outfits worked because each piece was simple and worn with complete confidence. We would skip anything that looks like a costume version of the seventies, like towering platforms or a wide paisley collar, and stick to clean shapes instead. A good pair of flares, a poplin shirt and a basket bag will get you most of the way there. The rest is attitude, which is the one part nobody can sell you.