Banksy takes credit for work at Oscar Wilde jail
The artwork shows a prisoner escaping on a rope made of bedsheets tied to a typewriter.
The elusive artist confirmed he was responsible in a video posted on his Instagram account.
The footage shows the artist carrying out the painting, and parodies the cult instructional videos of late U.S. 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 as he executes his work, while a soundtrack of friendly advice from Ross plays over the top.
Reading Prison closed to prisoners in 2013 and is best known for housing Wilde during his two-year sentence of hard labour for "gross indecency".
His final work "The Ballad of Reading Gaol" made the case for prison reform.
The Ministry of Justice, the listed building’s owner, is set to decide this month whether to turn into an arts venue.