Image copyright Getty Images Image caption The artist recently showcased his wares in Croydon

Banksy has launched his own official online shop, selling the stab vest Stormzy wore at Glastonbury, a tombstone and housebrick handbags.

But as ever with the artist, there is a twist - he's vetting potential buyers and wants to shut out art dealers.

Everyone must answer a question on the site to explain why art matters.

"An independent judge will examine the tie-breaker questions and select those applications which the judge finds to be the most apt and original," it says.

Image copyright Getty Images Image caption His works were removed from the Croydon store on Sunday

His popularity - and the fact prices are low compared with what the works could fetch on the open market - means demand is likely to far outstrip supply.

The elusive Bristolian artist's website adds: "Our judge is impartial and independent, and is a professional stand-up comedian." That comedian is Adam Bloom, a statement from Banksy said.

The artist said: "We can't ever weed out all the people who just want to flip for profit, but we can weed out the unfunny ones."

The Art Newspaper correspondent Anny Shaw told the BBC: "It's a tongue-in-cheek poke at the market while at the same time attempting to wrestle some control of it."

Many items come from an installation he set up in an empty shop in Croydon, south London, two weeks ago. The artist has been embroiled in a legal dispute with a company that he said wanted to claim his trademark because he had not used it for his own merchandise.

What's he selling?

Image copyright PA Media Image caption Stormzy wore the stab vest during his Glastonbury headline set

Stormzy's stab vest, described as a traditional English waistcoat "updated for modern times", is on the Gross Domestic Product [GDP] website for £850. That's a snip considering it was valued at "somewhere north of £200,000" by Joey Syer, co-founder of MyArtBroker.com, when it was revealed to be Banksy's handiwork.

There is a T-shirt bearing his famous girl with a heart balloon - with its bottom part shredded, imitating the canvas he remotely shredded when it was sold at auction last year.

There's a baby mobile featuring 19 mini CCTV cameras pointing at the cot, and a welcome mat made from life vests abandoned on the beaches of the Mediterranean. Cheaper items include £10 mugs painted by children based on his designs, and £30 charity shop T-shirts that he has tagged.

Can he really stop people selling them on?

"Please buy an item because you like it, not because you think it is a good investment," the site pleads.

Image copyright Getty Images Image caption Banksy's shredded artwork: A comment on the art market or marketing stunt?

Some saw his 2018 shredding stunt - moments after that picture had sold at Sotheby's - as a response to the eye-watering sums paid for his works. Art market adviser and analyst Ivan Macquisten says it was also "a terrific marketing exercise". He adds: "Whether he intended it as such I don't know."

Banksy has "always been very controlling about his market", Macquisten says: "He's got this whole idea about the art market being exploitative… which is great for somebody who's making so much money out of it!"

The online store's small print says Banksy's team have the right not to fulfil an order if the buyer advertises the item for resale before it's dispatched, or if they suspect it will be afterwards.

"Ultimately, how are you going to tell?" asks Anny Shaw. "That's why he's having this little game with the question you have to answer in the application process. He's playing with the vetting process. But there is a serious message, he is trying to police it to an extent."

But ultimately, an artist can't control who buys and sells their works, especially if there's no dispute about the authenticity.

So he is setting up his own eBay

Intriguingly, one of the links on the site goes to "Bbay", which is described as "the approved used Banksy dealership".

It's not live yet, and just has a photo of a man with eyes blacked out, who may or may not be Banksy (it's probably not) selling Banksy pictures at a car boot sale.

It looks like he will try to persuade buyers and sellers to use Bbay in the future, giving him some control over (and possibly revenue from) works that are resold.

"It looks like he is announcing an approved outlet for secondary market works, which is quite a departure and quite a bold move," Shaw says.

Is this about trademarks - or one big art stunt?

Image copyright Getty Images Image caption The £750 housebrick handbag is billed as "perfect for the kind of person who doesn't carry much but might need to whack someone in the face"

"For the past few months I've been making stuff for the sole purpose of fulfilling trademark categories under EU law," the artist said when he opened the Croydon installation. "Its not a very sexy muse."

Arts lawyer Mark Stephens, who has advised him, said at the time: "Banksy is in a difficult position because he doesn't produce his own range of shoddy merchandise and the law is quite clear - if the trademark holder is not using the mark then it can be transferred to someone who will."

But he has turned the fulfilment of EU trademark law into a typical Banksy event. "It's all very meta isn't it?" says Shaw.

"There are these very serious market messages and this trademark legal dispute - all very boring, turgid things if you look at them in isolation. But he's managed to flip it into something rather brilliant."

Macquisten says: "Damien Hirst has always said that the marketing of his art is part of the artistic process - in fact possibly the most important part. With Banksy, this whole idea about control is becoming part of the artwork itself."

And perhaps he will turn the responses to the question about why art matters into a new artwork of its own. The T&Cs on the online store point out: "You retain copyright in your response to the tiebreaker question, but you agree that we may (but shall not be obliged to) use or publish it in any media."

And the site even suggests punters may get less than they bargained for. "You are advised that GDP may prove to be a disappointing retail experience - especially if you're successful in making a purchase."

Analysis - BBC arts editor Will Gompertz

The shop, like a lot of Banksy's work, first appears as a whimsical publicity stunt: a joke to poke fun at the establishment.

But the reason his art penetrates public consciousness and endures is because there's usually more to it than first meets the eye. Art is about revealing truths - Banksy's almost always does that.

With the shop, he's trading on familiar ground - the relationship between art and commerce. Are they the same, as Andy Warhol famously said? Why does anybody want the product he's offering, which he warns might disappoint? What other shop would you go to which said its stuff might not be very good?

And yet a lot of people will. As you'll soon find out on eBay…

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