When conservationists discovered the walls of the Old Fort at Shoreham were teeming with lizards, their work slithered to a halt.

Reptile-lovers from across the county were eager to protect the hundreds of common wall lizards that have made the fort their home.

But members of the team sprucing up the historic fort insisted the work must go ahead.

Before the two groups could come to blows, a reptile expert came up with an ingenious solution.

Chris Davies, who works on behalf of The Herpetological Conservation Trust, suggested the lizards could have rubber tubes as their own "front door" to the walls of the historic building.

The tubing network gives the lizards access to the maze of nooks and crannies inside the fort while still allowing conservationists to seal the rest of the walls.

Mr Davies, who came up with the idea after he was contacted by lizard expert Steve Jones, said: "It is a simple solution, but it works. This way everyone is happy."

The colony of lizards is the only one in Sussex and one of only five across the country. They were introduced in 1974 and have basked in the sun there ever since.

Common wall lizards are not common, although they are widespread across Northern Europe. They are an endangered species and protected by the Bern Convention.

They are approximately 2in longer than the native common lizard and can grow up to 8in long. They have similar greyish, marbled markings to the common lizard but can sometimes be bright green.

Mr Davies, of Findon Valley, said it was impossible to estimate how many lizards lived in the Old Fort.

He said: "There must be hundreds, but it would be impossible to count them. Their big defence technique relies on speed and shyness, so they don't come out much.

"There's plenty of people around, plenty of cats and plenty of seagulls, which are themselves great predators. They have to be pretty savvy to avoid that lot."

Work on the Shoreham Port Authority-owned Old Fort is part of a wider conservation project along the beach. Last week the project received a boost when Adur District Council pledged £8,000 to fund the project manager's post for another year.

Adur planning officer Duncan Morrison said: "This is a community project looking at the whole area. We are planning to protect the rare plant life on the beach by designating it a local nature reserve. We are also hoping to create an interpretation centre looking into the history of the port."

The fort has stood at the head of the harbour for more than 150 years. It was set up as a defence against an invasion by Napoleon and was one of several so-called Palmerston forts on the South Coast.