The court heard that working practices were 'appallingly dangerous' and that similar conditions to those that led to the blast had occurred on three occasions before December 11.

Details of how the depot was managed have come to light in the row between Total and Chevron over who was responsible for day to day operations, and therefore who must foot the bill for the disaster.

Jonathan Sumption, acting for Chevron, told the court today (Tuesday) that storage tank alarms - designed to prevent spills in the event of overfilling - were routinely used as a method of gauging when a tank was full, against industry best practice.

He said that in the six months leading up to the disaster one filling in six, or one every three days, involved the use of alarms to decide when a tank was full.

Mr Sumption described how the alarms relied on gauges that routinely got stuck and that tank 912, source of the spill that caused the disaster, was particularly prone to problems.

"Working to alarms was the normal practice," Mr Sumption said.

"When the gauges stuck, as regrettably they often did, control room staff didn't notice.

"In the six-month period gauges stuck 21 times. Eighteen involved tank 912.

"The striking thing about these incidents was how long it was before anyone noticed.

"On the eighteen occasions it stuck on 912 it stayed stuck for between 22 minutes and eight hours.

"What happened on December 11 had very nearly happened on three occasions.

"Working to alarms is an appallingly dangerous practice if alarms are, to the knowledge of staff in the control room, liable to stick.

"If the phrase 'an accident waiting to happen' was ever justified, it was justified in the case of this terminal."

Residents, businesses and insurance companies are seeking damages of around £700million from Total and HOSL.

Justice David Steel said: "I am told there are a very large number of claims which are yet to be settled and in respect of which no interim payment has been made."

He ordered both sides to progress the settlement of claims within 28 days.

Des Collins, who represents 272 residents, said after the hearing he was delighted Total had finally accepted liability for the disaster.

"It's unfortunate the residents have had to go through three years of hard struggle to get to this," he said.

The case continues.