Just days after a new Banksy mural appeared in London's Kew Bridge, it was tagged by a fellow graffiti artist with a white signature sprayed on top of the randy rhinoceros. It's not the first time this has happened - in fact, the defacing of Banksy's artwork is so prolific and normalised that it has its own Wikipedia page, which lists some 50 artworks moved or erased. Last week, in the wake of the UK riots , the street artist undertook a nine-day painting spree, with exotic animals popping up all over London.

The artworks included a goat , elephants , monkeys , a wolf , pelicans , a cat , piranhas , and a rhino , culminating in a gorilla at London Zoo. But at least five in the series were stolen, defaced or moved to a secure place for their own protection, many within hours of their arrival. The rhino artwork now lives behind a plastic screen with security monitoring it.

Jasper Tordoff, a Banksy specialist at My Art Broker, says he has heard Banksy's depiction of a howling wolf on a satellite dish - that was removed by masked men within hours of appearing - is already being hawked between galleries. "It makes a profound comment on how we can't enjoy these things," he says. "And I don't know how people sell these things, frankly, because it's illegal and they're dealing in stolen goods.

" Please use Chrome browser for a more accessible video player This has led some critics to question if Banksy's fame now eclipses the political value of his work - after all, what is the point .