HOW TO SPOT ONE: Sporting the very chic-est in lux athleisure – including a pair of Alexander Wang X Rihanna leggings that cost £213 in a fevered eBay bidding war – the Catwalk Runner is of the opinion that if nobody sees you out for a run, it didn’t really happen.

If nobody sees you out for a run, it didn’t really happen

Every single part of their get-up is studiously coordinated, from their ‘adidas by Stella McCartney’ trainers to their limited-edition Monreal London energy gels (which are kind of surplus to requirements, as they’re only doing a 2k circuit of the city centre during their lunch break).

Once they become a parent, the Catwalk Runner will graduate to a Pram Speeder, hurtling their startled offspring around the streets in a 5ft-tall Swedish pram called a Bäböoschfnaffn.

HOW TO DRIVE THEM MENTAL: Tell them you love their “funky” vest, ask if they got it from Sports Direct.