London Fashion Week can often feel like a collision of two aesthetic worlds: a sophistication on the runways and a youthfulness in the streets. Seeing the rapport between them is among the highlights of attending the shows. This season, something about the outfits on and off the catwalk felt a bit more mature — maybe because London Fashion Week is celebrating its 40th anniversary this year.

Structural skirts brought a sense of refinement to the collections of brands like Erdem, Simone Rocha and Chopova Lowena. Refined could also describe the clothes at Edeline Lee’s debut show, which included a parade of dresses that evoked styles seen in travel ads and magazines from the 1950s. Even Jonathan Anderson, a designer known for his frog clogs and pigeon bags, seemed to dial up the seriousness of his playful approach: His new JW Anderson collection included frocks with sleek, flying-saucer-like silhouettes.

Quiet plaids and fancy-looking knits were some of the sartorial signs of maturity in the streets. Many of the best looks in the crowds felt elevated and had less of the D.I.Y. charm that the city’s fashion fans have been known to embrace. This was neither bad nor good; if anything, just a sign of how personalities can change with age.