To some it is art; to others nothing more than vandalism. But whatever your view, a mural painted by the graffiti artist Banksy on the side of a house in his home town of Bristol may soon be worth more than the property it is painted on.

When the house went on the market recently, several potential buyers insisted the mural must be removed. So the owners - fans of the artist - have decided to sell the painting - with the house thrown in free.

At an auction at Sotheby's this week, one of Banksy's works, "Bombing Middle England", went under the hammer for £102,000. Now the Red Propeller Gallery in Devon is hoping that the 25ft by 6ft mural in Bristol will sell in excess of £200,000, the market price of the house. Angelina Jolie and Brad Pitt are said to have paid this sum for a Banksy canvas last year.

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The mural, unusual because it does not use his trademark stencil method, "has a few trademark stamps", according to the gallery's owner, David Anslow. He said: "It is an advocate of direct protest art on walls and tongue-in-cheek satirical statements, which Banksy has become famous."

The owners will use the proceeds from the sale to set up a street art gallery at a derelict printworks adjoining the five-bedroom property.

The couple, who do not want to be named, bought the house as an investment and rented it out to students. They only discovered that Banksy had used the property after a picture of it was published in his book, Wall and Piece, at the end of 2005. The students renting the property more than three years ago did not notify the owners when the mural first appeared.

Mr Anslow said: "I believe the students knew Banksy and were worried about the owners' reaction. He was only locally famous then." He added: "The guy's a genius. It's just fantastic what he's done. He's turned a whole generation of disaffected youth on to art."

Local Bristolians and street artists alike hold the piece in high regard. "They will fight tooth and nail to keep this artwork," said Mr Anslow. "You'd expect the street artists to deface it and put their tags on it like they have done in other areas, but there is so much respect for his work around here."

Last year, Bristol residents were invited by the city council to decide whether a Banksy image of a naked man hanging out of a window on the side of a public building should remain. Of 500 people who responded on the askbristol.com forum, 97 per cent supported the work.

The gallery is selling the mural through sealed bids, which allows them to vet prospective buyers. The closing date is 1 April. But Mr Anslow insists this is no April Fool. "I suppose it is an unfortunate date. We chose it because the mural is the centrepiece of an exhibition we are holding called Urbanista."

The Red Propeller Gallery has commissioned Ocean estate agents in Bristol to deal with the sale. Assistant branch manager, Alec Jupp, said the property would be marketed as a piece of art for sale, but contractually the mural and the house would be linked. He added: "It's very different from the norm to be selling a piece of art work on the side of the house rather than the house itself. We hope there will be someone out there who is prepared to pay a premium for having an original piece of art by a cultural icon."

Banksy's agent, Steve Lazarides, has been notified about the sale, but was unavailable for comment.