Pull on your long johns girls! Thermals, previously the exclusive preserve of granddads, have gone from OAP underwear to celeb outerwear. How did that happen? LA brand Primp is selling out of its cute bunny and pony design thermal tops and leggings after a whole host of celebs (Mischa Barton, who wore the whole lot at once, Paris Hilton, Rachel Bilson and Lindsay Lohan) decided to don their wares…on the outside.

If you want to join the pyjama party, you can get your own at shopintuition.com for $65.[Charlotte Howells]