Race-fixing is fortunately extremely rare, but the Tripoli Grand Prix in 1933 has entered folklore as one event that was tarnished in this way. However, evidence suggests accusations levelled at those involved result from the inaccurately excitable recollections of a major figure in the sport rather than anything more sinister.

The opening of a state-of-the-art track in Tripoli in 1933 was supposed to herald a new era in motor-racing as well as providing another publicity coup for Benito Mussolini's imperial ambitions and a boost Pietro Badoglio, the new governor of Libya.

A grand prix had been held in Tripoli between 1929 and 1931, but had been poorly supported and a financial disaster. Undeterred, Badoglio, using the convincing argument the race was vital for the colony's profile, persuaded Mussolini to endorse and part-fund the project.

The result was a superb venue with all modern gadgetry, including electronic timing and start lights. The track was a testing one, eight-and-a-half miles long and fast, and no expense was spared to promote the first event in May. The top drivers of the day were lured to Libya to take part by huge prize money and royalty-style pampering.

The event should have been a landmark in racing history. Instead it has become tarnished with allegations of race-fixing among the leading competitors.

In a marketing move ahead of its time, the authorities organised a lottery in Italy where 30 tickets would be drawn on the eve of the race and each one would be allocated to a starter. The owner of the ticket of the winning car stood to receive 7,500,000 lire (about $250,000 at the time). And therein, according to subsequent accounts, lay the problem.

The story went that on the eve of the race, Achille Varzi received a visitor, Enrico Rivio, in his hotel room with an odd request - he asked Varzi to ensure he won. The reason then became clear as he explained he owned the winning lottery ticket associated with Varzi's car. The offer Rivio made was to pay Varzi half of the lottery prize money if he delivered - even that was more than twice the prize for winning the race - and produced a contract drawn up by a solicitor to that effect. Varzi, it is said, finished with a promise he would see what he could do.

The next day the track was packed with dignitaries and spectators sheltering from the intense heat. Marshal Balbo, who was to become Libya's governor later in the year and wearing his full military uniform, started the race, and all seemed to be going well as Sir Tim Birkin in a Masaratti led for four laps before being overtaken by Campari with Tazio Nuvolari and Baconin Borzacchini close behind. Varzi, the favourite, was in the middle of the field.

Nuvolari took the lead when Campari retired with Varzi, his Bugatti suffering from engine problems - some way adrift. However, Nuvolari pitted on the 27th lap and by the time he returned to the track Varzi was 30 seconds ahead.

At the start of the last lap, Varzi's lead was down to a few seconds, and as the crowd roared their approval, the pair came round the final bend with Varzi desperately clinging on as Nuvolari attacked. As they crossed the line Varzi was a couple of feet ahead. An exhausted Varzi was lifted from his Alfa and carried shoulder high by spectators to receive his prize.

Rumours that something wasn't quite right started circulating that night when Varzi, Nuvolari and Borzacchini were supposedly seen in their hotel drinking expensive champagne. Within hours, talk of a fixed result was widespread.

Even at the time there was enough gossip to prompt L'Auto Italiana to report a fortnight after the race: "Many people, without knowing the reason, did not really believe in this defeat. On the one hand, it is ridiculous to think that the two drivers had agreed a "fiddle" yet, on the other it is true that the two drivers (and Borzacchini, who retired) had made a pact with three holders of their [lottery] tickets. It would have not mattered who had finished first".

Varzi himself admitted a meeting had taken place between himself, Nuvolari, Borzacchini and the three lottery ticket holders ahead of the grand prix "to find a formula which did not contravene the sporting rules" of how to divide the money - but it took place in Rome and not in his hotel. Other stories have different drivers being made similar offers by ticket holders.

Such a loose agreement was not in contravention of the rules or even the law, even if it was morally dubious. It also meant that providing one of them won, which one did so was immaterial. That undermined suggestions Nuvolari had thrown the race, as did contemporary accounts of the battle over the last few laps.

Within a few months the episode had been forgotten as Borzacchini and Campari died at Monza in September. The fascist government in Italy also stifled the story which it felt reflected badly on the regime.

There the whole thing might have stayed but for the legendary Mercedes manager Alfred Neubauer. In 1958 he published his autobiography Speed Was My Life and in it he made some wild claims against the drivers. But Neubauer's book showed he was not averse to embellishing stories, and what's more, he was not even at Tripoli for the race. He was, nevertheless, on safe ground as Varzi, the last of the three drivers involved, had died a decade earlier.

Neubauer's account, however, is one that has gradually been accepted as fact, despite many glaring errors and it being completely at odds with what actually happened.