Revellers in fancy dress trashed an empty building during an illegal Halloween rave, eye-witnesses have claimed.
The 24-hour party, near Stonebridge Park Tube Station, began just before midnight on Saturday November 1 and carried on until the following evening.
About 2,000 people attended the event, leaving the building, in Abbeydale Road, Alperton, vandalised and littered with rubbish.
One party-goer said: "They (the organisers) demonstrated callous disregard for public safety, attracting people to an unlicensed event that had no health or fire safety procedures in place."
But reveller Voytek Stanley, 27, of Brighton, defended those involved, saying: "Not everyone here is out of their head. Most people have just come for a good time.
"There is all sorts here, teachers, office workers, solicitors. They come because it's cheaper and friendlier than a nightclub, and you can smoke."
He added: "Parties like this prove the Government's drug policy isn't working. Ordinary people just don't care if they say taking drugs is wrong."
Councillor Chunilal Chavda said the rave was irresponsible. He added:
"Anything that is a nuisance to the public has to be rooted out."
The building has been occupied by members of the group as a squat for several months.
But the rave went ahead despite a court order banning people from entering the building.
Police confirmed they did visit the property at about 11.30pm on November 1, but made no arrests and said no criminal damage was done.
A police spokeswoman said: "The police are liaising with the owner of the premises in relation to the security of the site."