Campaigners say Banksy’s Art Buff could return to Folkestone, after the work reportedly failed to sell at a Miami art fair.

And selling the painting at all on the open market could be difficult, according to insiders.

Hrag Vartanian, editor-in-chief and co-founder of art blog Hyperallergic, thinks this is because it has not been authenticated by Pest Control - a company that issues paperwork for genuine Banksys.

He said: “They [the works] aren't approved by Banksy's Pest Control, which means no reputable auction house will touch them. This impacts the value.

“I’m not sure I know of any major museums that shows non-Pest Control approved pieces.

“Considering there's ‘official’ Banksys available, I can see why few want to spend on unofficial ones.”

Sure enough, Art Buff – predicted to sell for about £450,000 – is thought to remain in the possession of New York’s Keszler Gallery, which curated the exhibition of Banksy’s work at Art Miami earlier this month.

“Considering there's ‘official’ Banksys available, I can see why few want to spend on unofficial ones...” - Hrag Vartanian, art writer

Campaigners from Folkestone’s Creative Foundation hope Art Buff’s "unofficial" status leaves a glimmer of hope the painting may yet return to the town, arguing it was created as part of the Triennial.

A spokesman said: “The Creative Foundation believes Banksy intended Art Buff to be part of the Folkestone Triennial as he posted a picture of it on his website saying it was "Part of the Folkestone Triennial. Kind of".

“We are very keen for the Banksy to return to Folkestone but this requires Banksy to confirm that his intention was for it to be part of the Triennial and a gift to the people of Folkestone.

“If Banksy confirms that he did intend to give Art Buff to the Triennial, then other claims to ownership would fall away.

"We would love the work to come back to Folkestone and feel that if enough people ask him, Banksy might confirm that he did intend to give it to the Triennial. Please Tweet or post on Facebook #banksy4folkestone."

However, American art dealer Stephan Keszler, owner of the eponymous gallery, has other ideas.

He says Bankys’s work is for “people with taste and money” and argues it’s “unreasonable” to expect the street art to remain in situ.

He said: “It's very unreasonable. Every complainer would stop complaining if Banksy would paint on their property.”

When asked if it mattered whether Banksy's work was removed from its original location, Mr Keszler replied: “Not at all. Without our involvement this and 90% of Banksy's street works would have been destroyed.”

Shortly after Art Buff was painted Shepway council covered it in a protective sheet of perspex.

Someone - possibly Banksy himself - returned to the painting and added a penis to the plinth, which was later erased.

Art Buff was removed from the wall of Palace Amusements in Rendezvous Street Art Buff on September 30, and placed in storage briefly before being shipped to American where it joined other "unofficial" Banksy works in an exhibition at Art Miami.

The Godden family, who own the arcade on which Art Buff was painted, said they intended money raised by the sale to go to a cancer charity set up in aid of Jimmy Godden.