“We can confirm that the artwork at the end of The Outlaws was an original Banksy, and that Christopher Walken painted over that artwork during the filming of this scene, ultimately destroying it,” a spokesperson for the BBC said.
The show is written and directed by Bristolian comedian Stephen Merchant and is filmed in Bristol.
From BBC’s website:
“The Outlaws, written and directed by Stephen Merchant, stars Hollywood veteran Walken as one of a group of minor criminals refurbishing a building for their community service. The last episode sees his character uncover the Banksy rat and two spray cans behind some wooden boards, and ask his supervisor if he should paint over it. The probation officer is looking the other way so doesn’t realise it’s a Banksy and tells him all graffiti must be painted over, which he does.” https://www.bbc.com/news/entertainment-arts-59236187