The trend spread out of Japan to the UK where in 2009 the Kigu brand was started. Their online store stocks the usual suspects you might have seen on the street like penguin, cow and tiger onesies, but also extends to the more exotic options of pugs and lemurs. The brand marketed their product to festivalgoers as a comfy costume clothing hybrid and soon a craze was born. This year the company is on track to make a rather staggering £2m turnover. Now it’s infiltrated our country with, listed as ‘Australia’s largest importer of animal onesies’, launching in 2012. (They claim their onesies ‘are guaranteed to increase your chances of random stranger hugs by 16%’. Yay?)

And the fad to wear these animal onesies out and about seems to be spreading faster than frozen yoghurt shops in an inner-city neighbourhood. Now we’ll admit there are some things that segue from festival wear to streetwear chicly. Embroidered dresses, slouchy boots, baseball caps. The basic rule is, can you imagine Kate Moss swanning around Primrose Hill in it? Animal onesies do not fall into this category.

The kigu fashion plague is plain baffling. After all they’re not especially flattering. You can’t easily go to the toilet in them. Oh, and you’re dressed as a giant penguin, there’s also that. But the trend seems to keep gathering momentum with animal onesies now stocked in mass market, Gen Y targeted fashion chains like ASOS and Urban Outfitters. Nightclubs are now hosting onesie parties (dress code: no onesie, no entry).

So how did they cross over from obscure Japanese fashion subculture and festival attire to having actual allowed-to-vote adults feeling comfortable walking down the street masquerading as a lion? Why are lambs literally dressing as mutton? Well, the animal playsuits got the celeb stamp of approval in a big way. Lily Allen appeared in public dressed as a dinosaur and the Pink Panther.