The latest officially confirmed Banksy artwork, “Mobile Lovers,” on display inside the Broad Plain & Riverside Youth Project on April 16 in Bristol, England. (Matt Cardy/Getty Images)

Picture this: You’re running a financially strapped boys club in a youth project in a city that’s seen better days. Things are so bleak you may have to shut down. Then, one day, a famous artist comes along quietly and creates a painting on a stray piece of wood in your doorway and disappears.

That’s what happened to a 120-year old boys club in Bristol, England. The artist was Banksy, the world-famous guerrilla graffiti artist. And experts told the BBC yesterday that the painting could fetch between $500,000 and $800,000.

The painting is called “Mobile Lovers.” Though he generally doesn’t like to mix art and money — he’s famous for that — Banksy has given his okay to having it auctioned off by the club.

He painted “Mobile Lovers” on a piece of wood that was being used to block a doorway in his home town of Bristol. When the club’s leader, Dennis Stinchcombe, happened upon it, he pried it off with a crowbar, intent on auctioning it off as a way to raise money for the club.

The town’s mayor, George Ferguson, threw a wrinkle in those plans, however, when he declared that the artwork was the property of the town and should be housed in a museum, which is where it is now.

Banksy confirmed that “Mobile Lovers” was his last month when he posted it on his Web site.

In a letter marked “private and confidential,” Banksy, who is famously laconic, told Stinchcombe:

As you know, I recently painted on a doorway near the club. This was meant as a small visual gift for the area — but apparently a financial one would have been more useful.

I don’t normally like to admit to committing criminal damage, but seeing as it looks like charges won’t be brought any time soon you have my blessing to do what you feel is right with the piece.

BBC News, which has a picture of the letter, reports that the letter has been authenticated.

Banksy has said in the past that he’d rather his work not be worth anything, but his works have commanded hundreds of thousands of dollars at auction. Last year, he sold his prints in New York’s Central Park for $60 apiece, making $420 total. One lucky, unwitting woman even bargained him down to half-price. The total was valued at more than $200,000.

It looks like everything will work out, as Ferguson appears to be honoring Banksy’s wishes.

“This is a proper resolution — we’ve done our job by looking after it and in the meantime we’ve collected a bit more for the boys’ club, and thousands of people in Bristol and farther afield have seen it,” Ferguson told the BBC. “This was never a case of Dennis and I not seeing eye to eye. Dennis has said that if it fetches as much as auction as it could do, the money will go not just to the boys’ club but also to youth projects in Bristol.”