She has withstood the waves, winter storms and now a huge inferno but this morning Brighton's West Pier was still standing - just.

More than a thousand people gazed from the beach and promenade as flames consumed the pavilion of the Grade I listed structure from 9.45am yesterday.

For three hours the flames raged, reducing what remained of the old theatre to a blackened iron skeleton.

Pockets of fire burst up throughout the afternoon as firefighters, who had watched helplessly from the beach, took to boats to damp down the flames and prevent the cast iron substructure from buckling in the intense heat.

A decision had been quickly taken to make public safety a priority but otherwise let the fire burn itself out.

The last flickers of flame died by about 7pm.

Despite the blaze all-but destroying the pavilion, the main structure survived its latest assault, a testimony to the brilliance of its Victorian architects.

The concert hall, which has partially collapsed into the sea in the past three months, was untouched.

And a controversial £30 million salvage package is still on course.

Detectives were last night scanning CCTV footage following reports of a black speedboat circling the pier, minutes before it was engulfed in flame.

A police spokesman later said it had been eliminated from their inquiries but there is little question the fire was started deliberately.

Geoff Lockwood, chief executive of owners the West Pier Trust, said: "The fire brigade and police will carry out thorough investigations but at this stage I'm puzzled as to what else has started it."

A spokesman for the Solent Coastguard said: "We are hopeful security cameras along the seafront might have picked up something."

Fire chiefs said the cause was "doubtful" and there were rumours of a firework rocket landing on the pier.

Station commander Phil Thompson, based at Preston Circus, Brighton, said: "There is no way it could have started on its own."

The West Pier, which was built in 1866, has been left to decay since 1975, when it was closed to the public.

Onlookers on the shore were stunned another disaster could befall one of Brighton's two embattled piers.

In December, part of the West Pier collapsed in rough seas and, just weeks later, a fire broke out in the ghost train on the neighbouring Palace Pier.

As the West Pier blaze took hold, many thought it was the final nail in its coffin.

But, apparently, one result of the blaze is that the cost of restoration may be reduced.

Developers St Modwen and the West Pier Trust are stillbehind the project.

By coincidence, Brighton and Hove City Council officers were meeting St Modwen representatives yesterday as the pier smouldered.

Council leader Ken Bodfish said: "We're still very upbeat and there is considerable confidence the restoration will still go ahead - and even some speculation the fire could save money in demolition costs."

Throughout yesterday boats were warned to keep well clear to avoid floating debris. Lifeboat crews said dangerous pieces of wood could remain in the water for weeks.

A coastguard spokesman said: "We put out broadcasts every four hours and have been putting out warnings."

Shoreham Inshore Lifeboat helmsman Dave Casson said: "There is an awful lot of debris drifting out with the tide.

"A lot of this is very large and could easily cause a hole in a boat if it hit it at speed.

"It will be out to sea for a long time and the majority is large pieces of wood with nails attached."

Some planks were expected to begin washing up at high tide last night, luring souvenir-hunters desperate to collect a piece of history.