By Chris Summers BBC News Online

One Sunday evening in June 1999, at the end of a service at St Paul's Cathedral in central London, one of the canons was approached by two foreign men who said they would like to donate up to $50m towards the refurbishment of the cathedral.

An American calling himself Ron Wood and a Canadian known as Anthony Foster, said that to free up this "gift" cathedral officials would first have to put up �100m in cash, which would be placed in a "blocked fund" bank account.

They were told their money was ring-fenced and could not be transferred to another account.

They claimed to St Paul's that the film business closed down at that time of year and there was all the cash floating around and they wanted to do something with it.

Detective Inspector Bob Wishart

The men, who claimed to represent a group of Hollywood film producers, sounded plausible and the cathedral authorities admit they were very interested.

Police believe the conspirators planned to empty the account of the cathedral's money and disappear.

Police tipped off

But the cathedral's registrar, Major John Milne, said they became gradually more sceptical and eventually called in the City of London police.

They mounted a deep undercover operation when they realised they were dealing with sophisticated international fraudsters.

Detective Inspector Bob Wishart, who led the inquiry, said: "They claimed to St Paul's that the film business closed down at that time of year and there was all the cash floating around and they wanted to do something with it.

"They said St Paul's was such a fantastic place and you want to get rid of all that scaffolding.

"It was a no-strings attached donation."

Hotel meeting

Then there was a change of tack.

Ron Wood and Anthony Foster dropped out but church officials were approached by a man who claimed he was from the United States Treasury.

He offered them a profit of $50m - enough to renovate the cathedral's dome - if they invested $100m in a Treasury-sponsored investment scheme.

Detective Inspector Bob Wishart, who led the inquiry, said the men claimed to be wealthy film producers and purported to be from a company called Helix.

They rented offices in Lincoln's Inn, central London, and one of the men claimed to be a retired banker.

There was another meeting at the plush Mandarin Hotel in Knightsbridge in a suite hired by a Saudi prince.

A man called Antonio Barea was introduced to the fundraisers at the meeting and claimed he was from the US Treasury.

Documentation

Mr Wishart said: "He produced several folders with various documentation about the investment and most importantly the demand for cash from St Paul's."

Four people were arrested after the meeting at the Mandarin Hotel and were charged with conspiracy to defraud.

On Friday the CPS offered no evidence against one of the men, Giorgio Rubolino, after accepting that he could not get a fair trial because two of his co-defendants, Joe Lowrey and Andrew Jalassola, had jumped bail and gone to the United States.

Barea has pleaded guilty and will be sentenced on 10 June.

The men known as Ron Wood and Anthony Foster are also wanted by police.

Police believe the group attempted a similar fraud on the Church of England pensions.

There was also an attempt to swindle �8m out of Marlborough College in Wiltshire.