Janusz Peciak of Poland won individual gold, but he insists he would not have been successful without the help of a rival. “I always say Jimmy Fox really helped me win my gold medal," he said.

Jim Fox, was a soldier by profession. In modern pentathlon he was a veteran competing in his fourth Olympics. In a plot that would have done credit to a John Le Carre spy novel, Fox uncovered a plot to cheat by a leading Soviet.

The 1976 Montreal Olympics had already been plagued by spiralling costs and delays in construction. Mayor Jean Drapeau claimed that “a man could no more have a baby than the Olympic Games show a deficit.” As it turned out Montreal tax-payers were still bearing the cost many years later. The Games were opened in an unfinished stadium and it also became clear that there would be a major boycott by African nations in protest at New Zealand’s Rugby Union tour of South Africa.

Few would have predicted that another major crisis would come in the sport of modern pentathlon. In Rio, the modern pentathletes will have to wait until the last few days of the Games to perform but in 1976, they were in action at the very start.

One day after the official opening, the pentathletes headed some 86 kilometres away from Montreal to the equestrian centre at Bromont to start their competition with riding.

Then as now, the horses were drawn at random and even the machine which made the draw for the jumping competition resembled a lottery machine. Critics said the course was too easy. Thirty-five of the 47 competitors achieved the target time and, of those, 11 gained the maximum 1,100 pentathlon points.

The next day came fencing. All competitors faced one another in an exhausting day long test of skill and nerve. In the opening contests, the British were drawn against the Soviets, a powerful combination which included world champion Pavel Lednev and Boris Onishenko, a soldier in the Red Army. Briton Adrian Parker fought Onishenko in the first bout and lost. The British had protested the result because they did not believe a hit had been made but the officials found nothing wrong. Now it was the battle of the veteran soldiers, Thirty-four-year-old Fox against the 38-year-old Onishenko.

When the two men lined up against one another, the light came on prematurely to indicate a hit for Onishenko.

“All I could think about was that Onishenko had a weapon that was not properly working, and then over a period of minutes, because he was going to put it back in his bag and because of the way he he wanted to put it back in his bag, I felt there was something dramatically wrong. I pushed out and had a hold of the blade itself.” said Fox .

Still unaware of the true extent of what had happened, British team officials attempted to calm Fox. The judges took away Onishenko’s sword to examine it.

“The weapon had definitely been tampered with. Someone had wired it in such a way that it would score a winning hit without making contact.” announced official Carl Schwende.

Peciak admits it was only after the event that he realised the enormity of what had happened in what became known as the “Onishenko Affair.”

“I was not really worrying about what the other athletes were doing. I was just completely focussed only on the sport, the Olympics was my goal, and I was trying not to get distracted . During the Olympic Games I tried to shut it out. Afterwards I heard all about the story, it was a great shock. It was very sad.”

“I was aware Jimmy was fighting the Russian and all of a sudden the light was coming on. I always say that Scotland Yard is the best in the world for investigation, but Jimmy Fox really helped me to win the medal, because if Jimmy had not caught him, Onishenko would have got away with this and would have won the gold medal instead of me.” said Peciak.

Other competitors were also aware of the drama.

“We turned around we heard the noise of what was going on the piste. There was Jim Fox grapping the epee.” said Jan Bartu, of Czechoslovakia.

“All of a sudden, Onishenko picked up his fencing gear, a guy in a suit on each side, and started walking out of the venue. There were Soviet agents sitting there.”

The Soviet news agency TASS reported the ‘’righteous condemnation’’ of Onishenko by the rest of the squad.

‘’That was it we didn’t see him again at the Games. I saw him many years after but not that day,’’ said Bartu, but as a medal contender he was determined not to let the drama affect him. "You just brush it from your shoulders, move on, get another bout , that is all that was in my mind, it did not affect me at all."

The incident was to have special resonance for Bartu. In competition as a junior, he’d overruled officials when they awarded him a hit against Fox., a gesture remembered many years later when Bartu joined the British Modern Pentathlon set up.

Many felt the commotion in Montreal cost Fox his chance of an individual medal. Visibly shaken, he tried to rationalise what had just happened.

“In the Olympic Games, there’s an awful lot of pressure, even in a country like Russia and in our own country too, a lot of pressure to do well. I don’t know, I suppose he just panicked and thought he could get away with it.”

Fox considered withdrawing from the competition but was eventually persuaded to continue, though his performance in what remained of the fencing was far below his normal form. Matters did not improve for him in the shooting, which back then was still a separate section.

The expulsion of Onishenko meant the Soviet challenge for the team event was ended. Strangely, the official film concentrated on the Hungarian competitors and made only brief reference to the sensation with one laconic sentence.

The swimming saw the British trio of Fox , Parker and Danny Nightingale move up to fifth in the overall standings. Czechoslovakia, with individual leader Bartu in their ranks were top, followed by Hungary and Poland. With one event to go, the eventual champion Peciak lay fourth in the individual competition, but he remained confident.

“I was a very good runner so I was sure before the start that I would win. I was sure that I would catch these guys ” said Peciak. “ I knew that I would catch Lednev because I was a better runner than him and better than the other people too.”

Peciak ‘s run of 12mins 29.7 secs was the third fastest of the competition. It earned him 1,318 points and sealed gold . By a happy coincidence as competition came to an end just the Polish football team arrived for their preliminary match against Iran. Lednev had to be content with the silver medal and Bartu took bronze.

In the team competition Great Britain did not just win a medal, but the gold medal. “There was something in Britain’s favour,“ wrote Neil Wilson later in the British Olympic Association report. “They were a team of runners.”

Fox himself described the course as “ruthless throughout with so many hills and dips that it was impossible, especially for a tall man to find a comfortable stride.” Yet all three had the runs of their lives and as the calculations were made it became clear that Great Britain had won team gold for the first time.

At the presentations, the three Britons received a single medal between the three of them and in the post event interviews Fox even made some jocular suggestions as to where it might be displayed. A double glazing firm later presented the team with unofficial replicas. .

When Peciak returned to Poland, he was voted sportsman of the year ahead of some illustrious contenders including high jumper Jacek Wzola, the national volleyball team and even the great Irena Szewinska , all Olympic Champions in 1976.

“People in Poland respected the sport unbelievably because they knew how difficult the sport was. There is not another sport where you test not only the physical but also the mental aspects at the same time. In pentathlon you have to be a good actor, for example in the fencing you have to be very aggressive , then the shooting is different again.”

Peciak might have made his name in water polo or even athletics but chose modern pentathlon. He later became Head Coach to the United States team and was closely involved with the International Federation in a technical capacity.

“I will never betray the sport,’’ he said. Even so , Peciak has seen many changes as modern pentathlon transformed from a five day event to something much shorter.

When I was competing you had to wait every day. It took a lot of extra stress, the night before every day you got stressed and every day you ‘d think about it. The stress is still there today but it is less.''