It's a feud that's been simmering for seven years -- or, if you leaf through the history books, since at least the Middle Ages.
From the moment in 2005 that London trumped Paris by four votes in the contest to host the 2012 Olympics, France has seethed -- furious that their neighbors and historical adversaries had scored a victory every bit as painful as Napoleon's humbling at the fabled Battle of Waterloo.
Now, French anger has burst out into the open.
In newspapers, on television debate shows and in scores of posts to social networks, Britain is accused of cheating its way to gold medals in the cycling velodrome and of stretching rules on the rowing course. British crowds have been blasted for failing to show enough support to rival nations' competitors, while organizers have faced scorn for failing to rein in judges deemed too harsh on French athletes.
British Prime Minister David Cameron has even defended his country's track cyclists -- who won a formidable haul of 14 medals -- from insinuations that their success must be the result of drugs or illegally modified bicycles.
"Of course there is no cheating," an indignant Cameron told France 2 television in an interview Wednesday. "There are the most strict anti-doping tests in these Olympics that there have ever been. There are very strict rules about equipment."
French cycling fans were already digesting the shock of Bradley Wiggins becoming the first British rider ever to win the prestigious Tour de France last month. To crown that feat, Wiggins and his teammates then won seven of 10 events in the Olympic velodrome -- once a French stronghold.
"It's driving the French mad," Cameron teased Thursday, speaking to BBC radio. "I think they found the Union Jacks on the Champs-Elysees a bit hard to take."
First Isabelle Gautheron, director of the French Olympic cycling team, stirred old animosities by suggesting Britain's gold streak may have been aided by subterfuge, hinting at the U.K. team's "magic wheels" and its little discussed work with the McLaren Formula One team on cutting edge technology to produce the quickest bike.
"They hide their wheels a lot. The ones for the bikes they race on are put in wheel covers at the finish," Gautheron was quoted as telling the French sports newspaper L'Equipe.
Then France's world champion cyclist Gregory Bauge -- beaten to gold in the individual sprint category by Britain's Jason Kenny -- hijacked a post-race news conference, demanding that his rival divulge the U.K.'s secrets.
Tempers reached boiling point when Britain's Philip Hindes suggested he had crashed his bike deliberately after a lackluster opening during a team sprint -- causing the race to be restarted. Hindes went unpunished; Britain later took gold.
Animosity hasn't been confined only to those on two wheels.
French rowing coaches complained bitterly after Zac Purchase and Mark Hunter of Britain were allowed a restart in the lightweight double sculls final. A seat in their boat had snapped off, but the French insisted the incident had happened after 100 meters of the race had passed -- meaning there should have been no leniency.
Guy Drut, who claimed the 110-meter hurdles gold in 1976 and serves on an International Olympic Committee commission, has complained that British crowds have cheered loudly only for their home athletes -- refusing to acknowledge the efforts of other nations.
A controversial decision that cost French boxer Alexis Vastine a win in his bout with welterweight Taras Shelestyuk of Ukraine also brought a furious online reaction from French fans, who castigated officials and organizers.
Complaints about favoritism for British athletes aren't all coming from the French.
After his team was beaten in a quarterfinal by Britain, Spain field hockey coach Dani Martin complained that some "countries are being favored" by referees.
"This is (like) a district tournament," Indian welterweight boxer Manoj Kumar said, speaking through a translator, after he was defeated in a close contest by Britain's Tom Stalker. "It's not an Olympic tournament. Cheating, cheating, cheating."