Police still have no idea how the fire which destroyed Brighton's historic West Pier started.

An investigation into what has been classified as an arson attack is continuing but there is little chance that any perpetrators will be brought to court.

Evidence at the scene that could have unmasked the firebug either went up in flames or is rotting at the bottom of the sea.

It is now nearly six weeks since the pier's famous pavilion burnt down in a spectacular blaze which saw flames shoot hundreds of feet into the sky.

The Argus later received a letter from the alleged arsonist who claimed he did it as a protest against the war in Iraq.

The author, who signed himself as Piers Burns, detailed how he got on to the pier and started the blaze.

He said the fire was started on the first-floor of the old theatre on a pile of timber.

The letter stated: "I spread five litres of petrol over the timber. The fire was started using a delay fuse.

"It did not threaten human life or other property. It was done in anger, a protest at the US/UK invasion of Iraq."

Experts for the West Pier Trust said the letter suggested the author had detailed knowledge of the interior of the pavilion. They said the claim was plausible.

Detectives and forensic experts are continuing to study the claim.

Detective Inspector Peter Laverick, heading the inquiry, said: "We have officers dedicated to the investigation but it is proving difficult.

"We still haven't established the source of the fire or the cause. It is being treated as arson. Our inquiries are continuing."