Elusive street artist Banksy claimed responsibility for a painting on the wall of a former British prison that once held playwright Oscar Wilde.
In doing so, Banksy appears to have thrown his support behind a campaign to turn the building in Reading into an arts venue.
The monochrome artwork shows a man escaping using a rope made of paper from a typewriter.
It appeared on Monday outside Reading Prison, famous as the place where Wilde served two years of hard labour for "gross indecency" in the 1890s.
His final work, The Ballad of Reading Gaol, made the case for prison reform.
Banksy confirmed he was responsible in a video posted on his Instagram account.
In it, he is shown stealthily stencilling and spraying paint to create the artwork, Create Escape.
The footage shows him creating the painting, and parodies the cult instructional videos of the late US artist, Bob Ross.
It opens with a clip of Ross saying: "Hello, I'm Bob Ross. I'd like to welcome you to the joy of painting.
"Got all your materials out, ready to do a fantastic painting with me? Good."
The action then switches to Banksy at work while a soundtrack of friendly advice from Ross plays over the top.
The Ministry of Justice, the owner of the listed building, is to decide this month whether to turn it into an arts venue – it closed as a prison in 2013.
The campaign to turn the former prison into an arts venue has the backing of actors including Judi Dench, Stephen Fry and Kenneth Branagh.
A spokesman for Reading Borough Council said it was “thrilled that Banksy appears to have thrown his support behind the council’s desire to transform the vacant Reading Gaol into a beacon of arts, heritage and culture with this piece of artwork".
“The council is pushing the Ministry of Justice, [which] owns the site, to make suitable arrangements to protect the image."