When normally fluid Lanvin's first silhouette is a wide-shouldered jacket worthy of Dragons' Den's Hilary Devey, you know something is up. Autumn's girl-as-boy gives way to spring's power woman, based on firm structure with moulded, sometimes stiff shapes, often in leather. There's volume in the upper half and a faultless, impressive simplicity, all grounded in modern couture cutting rather than 80s excess, despite an outbreak of studs as decoration. Best at Balenciaga, Céline, Lanvin, Maison Martin Margiela, Akris and Hermès, all of whom also featured dark, serious and autumnal colours like bottle green, burgundy and tan alongside summer white. A bid for the business market?

Perhaps it's the current focus on endangered sea life that has made designers turn to all things oceanic (rather than nautical), in subtle ways. From fishnet, trims of seawolf skin and fluid, curving lapels and peplums trailing like seaweed on tough tailoring at Givenchy, to graphic, wavelike Arabesques trims in the fabric used to seal scuba divers' suits on Stella McCartney's little dresses and tunics, this was inventive design. Chanel's underwater extravaganza, with iridescent sea blue sequins, soft fishnet knits and a plethora of pearls, especially in the hair, and the extraordinary encrustations of coral and pearl, including full hoods, face masks and breastplates on tattered, seaweed-like chiffon gowns, in Sarah Burton's Alexander McQueen collection, were very beautiful.

Haute couture is Paris design craft's USP, and the guiding principles of its 1950s heyday enthrall designers clever enough to give it a modern spin. Techno versions of traditional, full-bodied fabrics like gazer, graceful, volume backs and rich colour mix at Yves St. Laurent, new, pleat-necked variants on the famous Bar jacket and butter soft leather from interim designer Bill Gaytten at Dior, Liz Taylor-esque, crystal-trimmed Riviera tunics, trousers and caftan dresses at Giambattista Valli, and gloriously elegant dresses at Martin Grant are the best of the bunch.

It was huge in London and Milan – would Paris declare it too ordinaire? Not at all; they just made it even better, from the parade of angelic girls at Valentino – each showing a different handmade lace technique, some taking hundreds of hours – to Swiss designer Albert Kriemler (Akris) mixing his native lace designs in one simple dress, and Vuitton's tour de force of 1950s dresses and coats, with lace veiled in sugar plum coloured organza, big white buttons and lace collars, and many different lace motifs, not one featuring LV symbols.

Plain fabrics and cut are the more usual Paris strengths, but this season print is to the fore, following the lead of print-meister Dries Van Noten's beautiful collection, which mixes botanical art prints, 17th century landscape engravings and haunting night lightscapes from different world cities on simple shapes to a great and poetic effect. Other star prints: warm, subtly shaded tile and zigzag ornate from the Alhambra on silk and leather at Loewe, more tile prints beautifully mixed in large and small on silk separates at Stella McCartney, modern stripes based on a speeding racecar at Akris, sheeny Art Deco pastels at Issey Miyake, quilted Provençal sprig prints at Vanessa Bruno, and abstract florists at Cacharel.