He definitely got a permit for that which makes the whole thing even more laughable

There's no definitely about that at all. The city of Westminster issued a statement that seems fairly clear that they were as surprised as everybody else but are taking steps to protect it.

	▲	tialaramex 5 hours ago \| parent [-]
		Yeah, one of my distant friends is a councillor in a borough where Banksy did a mural years back and it was definitely much more about ensuring the standing "Send in workers to paint over any graffiti" reaction doesn't happen than some sort of "That's nice, the committee which issued the permit for this didn't tell me when it would happen". So far as she told me she heard about it the same way most people did, it was on the local news that morning.