Trouserless on the London Tube

Cold weather this afternoon and few sign of snow and chilly wind, but that hasn't stopped about 20 hardy types from taking part in No Trousers On The Underground 2010.

The annual "No Pants Tube Ride" was launched in New York City nine years ago by flash mob group ImprovEverywhere, and has become an annual fixture since. Cities with underground metro systems as far afield as Berlin, Adelaide and Mexico City have since joined in, with each global city holding its No Pants (or No Trousers) event on the same day each year. This is the first time the stunt has appeared in London.

The key to a successful No Pants ride, say organisers, is to behave as though nothing out of the ordinary is happening - keep a straight face, act as you normally would on the tube, and pay no attention to other trouserless tube passengers. The aim is to be as nonchalant as possible and appear as if you had simply forgotten to wear trousers.