ONE OF the smaller courtrooms in the Old Bailey, the main criminal court in London, has since September housed a single defendant, a sober suited Pakistani in his early sixties facing charges of false accounting. The atmosphere has been low key and purposeful; the casual observer may have assumed Abbas Gokal to be a prosperous accountant accused of a technical breach of the law.

But appearances are deceptive. Gokal is the biggest single fraudster to stand trial anywhere. At £800 million, his swindles dwarf those of Robert Maxwell, Bernie Cornfeld or any of the other giants of fraud.

One of three brothers, the former Karachi shipping tycoon rode the commodity boom of the early 1970s, cuddled up to Pakistan's strongman, General Zia and hosted big parties for the great and the good at international hot air conventions such as the World Economic Forum in Davos, Switzerland.

Respected as one of the new wave of Third World moguls, able to turn his ethnic background and religion to good account in dealing with Asian and African "commodity nationalists", Gokal appeared to be the first merchant prince to emerge from a Pakistan recovering from the 1971 war with India and consequent loss of Bangladesh. But all the time he was, as the other half of the $13 billion theft and plunder machine called Bank of Credit and Commerce International, a key player in history's biggest fraud.

BCCI and Gokal's Gulf Transport group were two sides of the same counterfeit coin. Neither had any money of its own; indeed both were insolvent many times over. But in the hall of mirrors that is banking, Gulf was just what BCCI needed. It worked like this BCCI was able to show all its dud loans to Gulf front companies as solid assets, while Gulf was fraudulently kept afloat by the injection of cash, some real, some illusory, from BCCI.

Not only were the Gokals BCCI's biggest customers, not only did they and BCCI prop each other up, but the Gokals may have been BCCI shareholders all along.

SUCH elegantly symmetrical documentary fraudulence can take you only so far, however, on your road to the world's biggest swindle; to go that extra mile you need to steal big.

Fortunately, BCCI had a large, juicy turkey ready for the plucking in the shape of its key shareholder, the hugely rich Sheikh of Abu Dhabi. Half a billion of his dollars were stolen to help keep Gulf's ships afloat from the late 1970s to the early 1990s.

But to what end? Investigators from Britain's Serious Fraud Office (SFO), while conceding BCCI's founder Agha Hasan Abedi became entranced by his own mystical mumbo jumbo, insist Gulf was always a commercial proposition. But "commercial" in the Pakistani context has its own meaning: Abbas's brother Mustapha (along with Abedi) was an adviser to General Zia. Beyond that, Gulf was a sanctions buster par excellence.

More serious still was Gulf's role in the procurement of nuclear technology. In 1991, the Guardian newspaper of London told the world that BCCI had bankrolled a secret three nation consortium (Libya, Pakistan and Argentina) seeking to assemble atomic weapons. What the Guardian could not say, because of libel danger, was that Gulf was suspected of providing the transport.

It was this suspicion that helped prompt the US authorities to propose a deal with Gokal in July 1994. He would leave the sanctuary of Karachi, fly to New York and name any US subjects involved in nuclear wrongdoing; in return, not only would charges be dropped in the US but, the suggestion was, the British would also be elbowed into grudging acceptance that Gokal made a better witness than defendant.

Five days before Gokal's scheduled Karachi New York flight, the Manhattan district attorney's office telephoned Detective Sergeant Douglas Reeman at the SFO. Gokal was winging in any questions the British would like put to him? Det Sgt Reeman gave a hurried "No", got off the telephone and alerted his seniors. By Friday, a warrant had been issued.

Gokal's flight had to refuel at Frankfurt. The Germans agreed to evacuate the aircraft "for security reasons"; Gokal, presumably smelling a rat, stayed on board with his wife. He was found and arrested.

The prosecutors in the London trial stated that "from 1985 through to 1992 at a time when... (Gokal) knew perfectly well that the Gulf Group, we allege, was insolvent, he lived a lavish lifestyle around the world". He and his immediate families benefited from the frauds.

Loans - vast loans - were approved without documentation. This mattered little in the early 1970s, when Gulf rode a worldwide shipping boom, itself a by product of the last heady surge of growth. It mattered rather more as world shipping hit the downturn of the late 1970s.

Multi national, BCCI Gulf was able to avoid exposure by ensuring no one bank regulator would see the whole picture. Even so, a few rays of light broke into the crazy house of BCCI, one of them a confidential report by the US bank regulator, the Office of the Comptroller of the Currency, in February 1978. At that time, BCCI's lending to Guff amounted to three times its total capital and 30 times the accepted ratio.

This aspect of the fraud - the keeping afloat of Gulf Group at all costs - formed Count One against Gokal, a false accounting charge in that he had forged huge numbers of letters, guarantees and minutes of meetings to make possible the loans. Millions were secretly pumped into the group by BCCI; simultaneously, the bank was able to book vast, fictitious profits from the "interest" on the loans.

Gulf gobbled cash; eventually a new source of funds was needed. The SFO said: "In order to satisfy Gulf's huge demands, BCCI had to find more money from its depositors and, when even more money was needed, from another source. This was the private funds of the Sheikh over which BCCI had control and of which they stole in excess of $500 million in relation to the Gulf Group alone."

Auditors, of course, are put on earth precisely to spot such chicanery, one good reason why BCCI took care to have separate auditors for its two main arms, BCCI SA and BCC (Overseas), ensuring no one firm would have oversight of the bank's tangled affairs.

But that changed in 1987, after a wild spree in foreign exchange, commodities and options markets left the bank "little more than an empty shell". Bank regulators in Britain and Europe heard rumours of huge losses; the affair allowed them to tighten their grip on BCCI. Henceforth, the whole bank would be audited by a single firm of accountants, Price Waterhouse. This development led directly to the allegations in Count Two against Gokal: "The setting up of a huge false financial structure in 1987."

Whereas Count One alleged fraud designed to keep Gulf in business, Count Two alleged a "mirror" fraud to keep BCCI from going under. At all costs, the truth had to be hidden from Price Waterhouse; auditors had to believe the loan book was spread prudently among many different borrowers.

Offshore companies (Liberia, Panama, the Caribbean) were provided with directors from among the clerks and typists of Gulf's Geneva offices. "These employees were told to sign, any false documents which were necessary". Bank accounts in New York were used, together with the sham offshore companies and regular Gulf companies, "to make it look as if real commercial activity was taking place when, in reality, millions of dollars were going round in a circle every day" according to a route planned by Gokal.

By the late 1980s, however, BCCI had made a fatal mistake. The bank had turned to servicing the needs of the drug barons. In so doing, it had aroused US anti narcotics crusaders; a conviction in 1990 for drugmoney laundering in Florida began the year long slide to the shutdown of July 1991.