Birkenstocks are back! And now that summer is well and truly upon us, we’re full-on embracing the slip-on sandal. It’s high fashion meets high street, with just the right amount of nostalgia sprinkled in. Think Kate Moss wearing a white pair in her iconic Corinne Day shoot in 1993, Céline's super-luxe versions in the SS13 collection, a host of directional street style snaps and your mum’s sensible ‘comfort first’ advice. So, how to wear Birks now? They're perfectly matched with a pair of boyfriend jeans, crop tops, floaty floral minis and aplomb. Just ask Ashley Olsen.