Puzzled passers-by couldn't believe their eyes when they spotted a naked woman on the roof of an arts studio in the East End of London.
"Right now at #toynbeehall," Raquel Rodrigues wrote, uploading two pictures of the woman perched on top of Toynbee Studios, in the centre of the capital. "What's happening? #nakedwomanonroof".
One witness told the Evening Standard : "I don't know how she got away with it - if I was walking around naked I'd be arrested.
"There are lots of businesses around, people were having a peek and then going back to work."
The bizarre event, which lasted four hours in freezing cold weather, was later revealed to be a piece of performance art by the artist Poppy Jackson.
Toynbee Studios said: "The piece investigates questions relating to temporality, the body in site, representation and gender through consideration of the use of the body in performance as an activist practice.
"The work interrogates the boundaries, access points and interaction between 'interior' and 'exterior' categories. Physical action dually presents the female body within a process of claiming space, whilst attempting to exist itself as deterritorialised space."
Jackson had previously made headlines after calling for donations of menstrual blood for an art project.