From Keira Knightley and Alexa Chung at the Serpentine's annual Summer Party last night to Kate Middleton on her royal duties in red, we round-up the best fashion moments from the week so far...

This week's celebrity fashion round-up

James Righton and Keira Knightley

Suki Waterhouse, Bradley Cooper and Pharrell Williams

Cara Delevingne

Naomi Campbell

Alex Chung

Lily Allen

Gemma Arterton

Princess Beatrice, 1 July

Princess Eugenie, 1 July

Amber Le Bon

Samantha Barks

Nicky Hilton

Arizona Muse

Duchess of Cambridge

Melissa McCarthy

Sharon Stone

Jennifer Lopez

Helena Bonham Carter

Tess Daly

Kerry Washington

A-list fashion round-up: from Keira Knightley at the Serpentine Summer Party to Kate Middleton on her royal duties