...and an update: Banksy's Web page is now completely blank. Still not barking.
In the meanwhile, rumours say the the happening might have been arranged by the crew Czon and Underground, but, crucially, with Banksy's explicit approval. They have denied it, but as we're in conspiracy theory territory anyway, I proclaim the denial to be a very suspicious fact in itself.
Czon, in the meanwhile, is a good illustration of one of the shortcomings of street art. There's a woman involved in the crew, and she's apparently welcome as long as she's willing to be depicted without any clothes on.