A parade of semi-naked Londoners hit the Underground on Sunday afternoon to take part in the annual No Trousers Tube Ride.
Despite biting temperatures in the capital, attendees donned their tighty-whiteys, budgie smugglers and whatever else needed to protect their modesty – while showing off a lot of leg.
Started in January 2002 with only seven people in New York, the craze has spread around the globe and this year’s London iteration attracted hundreds of participants.
Speaking to the BBC, the event’s original creator Charlie Todd said: ‘The whole point is just to create unexpected moments of joy, delight and confusion.’
He added: ‘It’s meant to be a bit of harmless fun. Certainly, we are living in a climate where people like to have culture war fights and my rule in New York was always that my goal is to amuse other people, to give people a laugh.
‘It’s not to be provocative or to irritate someone so hopefully the spirit of that continues.’
After gathering at the entrance to Chinatown, dozens of folk made their way through the icy streets to the Piccadilly Circus Underground station in central London where they boarded their first train – at this point still fully-dressed.
The only hiccup was that the cars were so crowded due to the cold weather that some people didn’t have the space to shed their trousers.
‘There’s so much bad, so much not fun going on,’ said ringleader Dave Selkirk, a 40-year-old personal trainer. ‘It’s nice to do something just for the sake of it.’
Scantily-clad participants posed on platforms, rode trains and took selfies – much to the bemusement of locals who hadn’t got the memo and tourists alike.
Mr Todd, a comedian, came up with the idea that it would be funny if someone walked onto a subway train in the middle of winter wearing hat, gloves, scarf – everything but trousers.
He told the BBC: ‘It would be unusual in New York, although you can see anything on our subway system, but what would really be funny is if at the next stop, a couple of minutes later, when the doors open and additional persons got on, not wearing trousers as well.
‘And they act like they don’t know each other, and they act like – it’s no big deal and they just forgot their trousers.’
The idea took off, and no pants days have been since been held in cities as diverse as Berlin, Prague, Jerusalem, Warsaw and Washington, D.C. – with London holding its first event in 2009.
Basil Long, a lawyer, showed up at the meeting point in a down coat and hat on a freezing winter afternoon.
But after his journey underground in the warm tunnels of the Tube, he had been transformed, wearing only a white shirt with bold rainbow stripes, pink underwear and Underground-themed socks.
‘I just saw it online and I just thought, why not? It’s always a question, isn’t it?’ he said. ‘When someone is asked why they climbed Everest, they were just like, why not?’
But Miriam Correa had a purpose. The 43-year-old chef wanted to come because she had seen pictures of previous no trouser rides that featured lots of thin, scantily clad women.
‘I am a real woman,’ she said, adding that there was no reason to be ashamed of her shape. ‘All bodies are perfect.’