Athens 2004 was rocked when Ireland's Cian O'Connor was stripped of the Olympic gold medal he had won in show jumping after his horse, Waterford Crystal, tested positive.

O'Connor was one of four riders banned during the Games, a figure replicated at the 2008 Olympics when Norway were stripped of the bronze medal they had won in the team show jumping event in Hong Kong, where the equestrian events took place.

Such was the controversy generated by the drugs scandals that some well connected experts claimed that equestrian's place in the Olympics could be under threat unless the problem was taken seriously. 

"The FEI had a really steep mountain to climb after Athens and Hong Kong, but we had a clean Youth Olympic Games, a clean FEI World Equestrian Games and now we've crowned it with a clean Olympic Games in London," said Princess Haya, President of the International Equestrian Federation (FEI). 

"We knew that fair play and clean sport was the only way to produce top sport in the Olympic equestrian events and we are very proud that we have achieved that goal.

"The fact that all human and equine samples came back negative demonstrates the success of the FEI Clean Sport campaign, which has resulted in a major reduction in the number of positives in the Olympic disciplines over the past two-and-a-half years."

Princess Haya, President of the FEI, has hailed London 2012 as the "best Games ever for equestrian sport"

During London 2012, all the medallists' horses were tested, plus all fourth-placed horses.

Random testing was also carried out, with horses being picked by computerised selection.

For human testing across the Games, all top four finishers, plus two other athletes selected at random, were tested by the IOC, along with other individuals selected at random.

"We had a rigorous and comprehensive testing programme in place," said Princess Haya.

"These were the most tested Games ever and we also tested for more substances than ever before.

"We worked hand in hand with the Horseracing Forensic Laboratory in Newmarket and thank them for the speed with which they processed all the Olympic samples so that we could maintain a level playing field throughout the Games.

"The equestrian community shouldn't be thinking of this as a triumph; having a clean sport should be our normal day to day business, but now that we've had three major championships that were the most heavily tested ever and they were 100 per cent clean, we can hold our heads up high and say that yes, this is a victory."

Princess Haya's drive to introduce new drugs testing procedures after the 2008 Olympics met with opposition at the time but she believes the ends have justified the means.

"We haven't reached this point by resting on our laurels, there's always work to be done and I am incredibly proud of the FEI's performance over the four years since Hong Kong," she said.

"This has been a real team effort, which was kick-started by the recommendations of the Clean Sport Commission headed up by Professor Arne Ljungqvist and the Stevens Commission, lead by Lord Stevens.

"The National Federations and the athletes and their support teams, as well as the team at FEI Headquarters have all played a major role in this success.

"Our community has really embraced the Clean Sport campaign."

The result is also a triumph for Professor Arne Ljungqvist, the chairman of the International Olympic Committee's Medical Commission and vice-president of the World Anti-Doping Agency (WADA), who chaired the FEI Clean Sport Commission.

"I am very happy to hear that the Clean Sport campaign has led to such a successful and clean Games and would like to congratulate the FEI," he said. 

Ljungqvist had been assisted by Stevens, the former Commissioner of the Metropolitan Police best known for leading the inquiry into the death of Princess Diana.

"To have totally clean Games at London 2012 is the best possible endorsement of the FEI's Clean Sport campaign," he said.

"I wholeheartedly congratulate the FEI on this success which is due, in no small measure, to the huge amount of work that has been done on education within the equestrian community."

This year's Olympics marked the centenary of the FEI and Princess Haya claimed that she could not have thought of a better celebration at Greenwich Park, which although a controversial choice of venue proved popular with riders, spectators and television executives.

Nick Skelton, riding Big Star, helped Britain to the team gold medal in show jumping, one of three won by the home country at Greenwich Park

Britain finished top overall with a total of five medals, including three gold, ahead of Germany, whose riders won four medals, two of them gold.

"The London 2012 equestrian events were really incredible and Greenwich was a wonderful venue," she said.

"We could not have wished for better sport and we now have a whole new fan base, which has to be the best legacy we could ask for.

"These were the best Games ever for equestrian sport."

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