This artwork by Banksy is a cartoon of the royal family waving from a balcony where they often appear for the public. It dates back to 2001, and has suffered several near-paint overs throughout its existence.
Notably, in 2009, Hackney Council had made attempts to cover the artwork with black paint after they served an enforcement notice for graffiti removal to the property owner. The building's owner intervened, preventing the act. However, remnants of the black paint can still be seen.
Bonus fact: a variation of this artwork was used by the music band Blur as the cover art for their 2003 single "Crazy Beat".
Cover photo: ceridwen / Banksy in Stoke Newington, detail / CC BY-SA 2.0