Banksy pulled off an audacious stunt to produce what is believed to be his biggest work yet in central London. The secretive graffiti artist managed to erect three storeys of scaffolding behind a security fence despite being watched by a CCTV camera. Then, during darkness and hidden behind a sheet of polythene, he painted this comment on 'Big Brother' society
heads up: this is a pretty old post, it may be outdated.
The article cover the entire story nicely. But I think I'll just leave it at a picture is worth a 1000 words.
Daily Mail