Around 100 people have let their trousers down on the London Underground “just for fun”.

The No Trousers on Tube Ride has become an annual tradition on the busy transport system.

One of them, William Skannerup, said that he took part after going through a “terrible breakup” and wanting to “do something different”.

“My game plan? To look as cute as possible and get a picture to use on my dating profile,” the 32-year-old said.

Once inside the train, Mr Skannerup and his fellow participants – wearing coats, hats and gloves – dropped their trousers.

People take part in the No Trousers on Tube Ride event on the London Underground

Commuters blushed, laughed and shielded their children’s eyes at the barefaced spectacle.

“Nothing to see here,” one man told his son.

Inspired by an event, launched in New York in 2002, the challenge has become an annual ritual in London since 2009, said organiser Dave Selkirk.

“In New York, it’s called ‘No Pants’, but that means something different in London,” where pants refers to underwear, he explained.

The brief? Participants are told to keep their underwear on and are encouraged to wear “low-key” lingerie so that “it looks like you’ve just forgotten your trousers”.

“The world is a rough place at the moment, and it’s lovely to have something that is just for the sake of fun,” Mr Selkirk said.

People take part in the No Trousers on Tube Ride event on the London Underground

Mexican couple Daniela Garcia and Fran Ruiloba joined in the revelry after hearing about the event last year.

“I love it, it’s so cheeky, it’s so English,” Ms Garcia said.

“It’s not illegal but like pushing the envelope a little bit, I like it,” added the 28-year-old lawyer.

“I feel silly,” Mr Ruiloba, a 34-year-old doctor, said.

“Right now we’re just happy to take our pants off and see where that takes us.”

“It’s one of the best public transports in the world. So, if I’m going to be without trousers, I think London’s the best place for it,” Ms Garcia added.

People take part in the No Trousers on Tube Ride event on the London Underground

Will, a 28-year-old working in marketing, said that he might get cold feet when the time comes to bare (almost) all.

“You’ve got to try all the unique things in London … I think it’s important to do stuff that’s pushing the line a little bit,” he said.

Did he do anything to prepare for the big day? “I did some squats before,” Will revealed, “to look good”.