An art dealer who initially valued the Cheltenham 'Spybooth ' Banksy at more than a million pounds now says it's effectively worthless.

Cheltenham borough council commissioned a report which found it has no commercial value.

The mural appeared on the the house in Fairview Road, Cheltenham, on April 13th 2014. It shows three secret agents eavesdropping on conversations at a phone box and is widely interpreted as being a side swipe at the role of GCHQ operations in Cheltenham.

The GCHQ 'doughnut' building is less than two miles from the house which is owned by David Possee. It is believed Banksy chose the house because of the position of the wall and the now famous phone box in the street alongside it.

Mr. Posse was offered £650,000 by an American collector for the painting when it first appeared but the offer was withdrawn when the mural was listed as a result of an application to the Council.

Mr Possee had authorised the Council to commission separate valuations for the building and the mural in order to arrive at an acceptable selling price for his property.

Giving his reaction to the recent valuation, Mr Possee said he wasn't surprised and that he hoped the work could be restored. He also remained philosophical about losing a potential fortune saying "what you never have, you never miss."

A local businessman has offered to buy the property and restore the Banksy for the benefit of Cheltenham.