A London court has found two property entrepreneurs guilty of fraud for their part in a scam which conned the Allied Irish Bank (AIB) and Bristol & West Building Society out of £740 million.

Achilleas Kallakis and Alexander Williams, business partners, were found guilty of what was one of the most complex commercial property fraud cases committed in the past decade as their trial at Southwark Crown Court drew to a close.

The two men were told that a prison sentence of “some substance” was inevitable after a majority verdict found them guilty of obtaining £740 million worth of fraudulent loans from the banks between 2003 and 2007.

The jury concluded that the pair had forged overriding leases and other paperwork, which they claimed had been signed by Hong Kong property giant Sun Hung Kai properties.

They were also found guilty of illegally obtaining a loan for £26 million from HBOS in order to convert a ferry into a super-yacht.

A third man, Michael Becker, is also alleged to have conspired with the defendants while he worked as a lawyer and businessman in Switzerland.

Becker was reportedly closely involved in the fraud and had a position as a director of several firms present in the fraudulent loan agreements as “borrowing companies”.

Kallakis and Williams were first charged in September 2011 with two counts of conspiracy to defraud, 13 counts of forgery, five counts of fraud by false representation, two counts of money laundering and one count of obtaining a money transfer through deception.

B&C previously reported that between 2003 and 2007 the pair had targeted AIB and HBOS to gain cash advances of nearly £740 million, leading to losses accrued by AIB of around £60 million and by HBOS of £5.8 million.

The loans in question were secured against 16 properties, including some of London’s most exclusive commercial properties acquired during the pre-credit crunch property market “boom-time”, as the pair operated under the name of The Pacific Group Family Trust from an office in Mayfair.

The pair had denied all of the charges against them, though the jury maintained that Williams had forged the overriding leases while acting on Kallakis’ orders.

A B&C investigation in 2011 found that a previous colleague of Mr Kallakis considered him to be “a short-tempered bully who boasted he was a multimillionaire with a family trust fund”.

Kallakis and Williams will be remanded in custody until 17th January when they will face sentencing.