A Banksy painting that appeared on a public toilet block in east London, only to disappear after it was vandalised and painted over, has been rediscovered and restored in Carlisle.

Known as the Snorting Copper, the image by the elusive graffiti artist, shows a uniformed policeman on his hands and knees snorting a line of cocaine.

Developers Jonathan Ellis and David Kyte uncovered the painting after they bought a disused site in Shoredith, Hackney, London.

They plan to return the now restored painting to its original site next month so the general public can see it.

The painting had been vandalised, then spray jetted, painted white and then boarded over.

In a complex operation, the entire wall was cut out and sent for restoration at The Fine Art Restoration Company in Carlisle.

Chris Bull and his team have painstakingly removed a heavy layer of industrial white paint as well as graffiti, and done other restoration work on the piece.

Mr Bull said: "It took 12 to 16 weeks to complete. We had six people working on it.

"It was quite complicated because of its weight and size."

Mr Bull told The Cumberland News said: "We used different solvents to soften them and scalpels to peel them back.

"The painting had been heavily vandalised by an angle grinder."

The painting arrived in the city on a lorry after carefully being transported up from London.

Mr Bull said: "Banksy is a massive story. We restore work for a lot of famous artists but Banksy is a big deal.

"If you google Banksy the number of stories about him on a daily basis is insane."

The cost of the piece is said to be £1.25m

The piece, now restored, is 2.2m wide and 1m high.

The artwork will be bolted to a concrete floor. It weighs 2.5 tonnes and will be protected by reinforced glass, alarms and CCTV. In its steel frame, it is about 2.5 metres wide by 1.5 metres high.

Mr Ellis said: "We’re putting it back in exactly the same location it was painted on the toilet block, but we’ve put it back on the inside of the glass, so it can’t get vandalised or damaged. We’re lighting it up 24 hours a day so you can see it."

Banksy, known for his stencil-based images, has maintained his anonymity, despite repeated attempts to unmask him.

Describing himself as a “quality vandal”, he has made his name by poking fun at authority figures through artworks in public places.

Stencil enables him to work at speed, quickly disappearing into the night.

In July, his Girl with Balloon – in which a child watches her heart-shaped balloon drift away – was voted Britain’s best-loved work of art, ahead of masterpieces such as Constable’s painting The Hay Wain.

The Snorting Copper will be unveiled at its original site in Shoreditch, Hackney, on October 5.

Mr Bull will attend the unveiling.