The invitation for Stella McCartney’s fashion show in Paris came in a glossy pouch with “I am 100% compostable (and so are you!)” printed on it. Inside was a freebie with purpose: a pair of yellow socks made from 85% upcycled yarn using no water, chemicals, dyes or pesticides.

In a socially conscious climate in which more and more fashion brands are pledging their commitment to sustainability, such details matter. But McCartney has been exploring ethical fashion since she set up in 2001, when it seemed like an eccentricity – or even a nuisance – to many in the wider industry.

Seventeen years later, McCartney’s winter show on Monday came at a crucial moment for her company, which is currently in talks with the French luxury conglomerate Kering – which owns 50% of the brand – about McCartney buying her share back.