Banksy taken off wall by German now worth £300,000

So when the painting, called Old Skool and featuring four pensioners dressed in hoodies and baseball caps, vanished, residents were understandably distressed.

It was replaced by a black dotted line marking where its edges had been and the word "collected" painted inside.

Today, it emerged that, despite conspiracy theories circulating on the internet, the mural has neither been stolen, nor removed by Banksy himself as a publicity stunt, nor accidentally painted over by council workers.

In fact, the owner of the garage has sold it - for £1,000.

The buyer spent about £30,000 having the image "peeled" from the wall by a specialist firm but experts say he still got a bargain because the original could be worth up to £300,000.

The mural's new owner has chosen, like the artist, to remain anonymous but he is thought to be a German man in his thirties who works in advertising.

Olly Pugh, manager of Clerkenwell Motorcycles in Clerkenwell Road, insisted the building's owner was happy with the price he had agreed for the painting.

He said: "No one knew too much about Banksy at the time and he thought, 'If some idiot is going to give me £1,000 for a mural that's great.'

"Part of the deal was that he will get a life-size reproduction of the mural."

The picture was removed by Tom Organ of Wall Paintings Workshop in Kent. It took Mr Organ, who normally helps restore medieval wall paintings, six weeks to complete.

He said: "We stuck some film over the top of the mural with an adhesive and gradually cut and peeled away quarter-millimetre-thick sections of the paintwork.

"We put the pieces back together like a jigsaw on a new support and then removed the film with a solvent that wouldn't damage the paint.

"I think my client was looking for about six months before he found a conservation company that could do the job but the techniques have been around for years. They were used to rescue paintings in Florence from the floods in the Sixties."

He added: "It's ironic because I've spent most of my life trying to keep paintings on walls."

Two other Banksy pieces that Mr Organ removed from walls - Bombing Middle England and Driller Rat - are among an exhibition of the artist's work that opened on Friday at the Andipa Gallery in Knightsbridge.

An Andipa spokeswoman said: "Alongside canvases, we are displaying a few pieces that were removed to give viewers an idea of his work, but we are not selling them - we have a firm belief that street art belongs on the street for everyone to enjoy and don't want to encourage people to take works off the street."