LONDON – HERE are some Olympic images that organisers have not approved: A hooded youth making off with an Olympic ring; the same multicoloured hoops turned into toasters; a dog doing something a bit rude to a London 2012 mascot.

The guardians of the games are vigilant about protecting the integrity — and the commercial clout — of the Olympic brand. But even they can’t stop the irreverent spirit of artists and craftspeople, who have responded to the games with a cheeky mix of celebration, scepticism and satire.

One street artwork in the southwest England city of Bristol — attributed to the artist Criminal Chalklist and reproduced on T-shirts for sale in London street markets — shows a masked and hooded youth sneaking off with one of the five Olympic rings.

Another T-shirt depicts The Beatles crossing a London street in the famous photo from the cover of “Abbey Road,” the Olympic rings tucked under their arms.

Other images have sprung up around east London — home to many of the city’s artists as well as to the July 27 to August 12 Summer Games. Those include the rings turned into kitchen appliances by the Toaster streetart collective and Teddy Baden’s painting of an amorous canine’s encounter with one-eyed mascot Mandeville.

“It’s just a cheeky little thing,” said Baden, who like many here admits to having an ambivalent attitude to the games. “It’s a quite British thing to kind of take the mick (poke fun) a bit. It’s not malicious.”

That humorous spirit may be why much of London’s games-themed street art has managed to escape the attention of Olympic brand enforcers, who are zealous about defending trademarks of the event and its sponsors.

Lee Bofkin of the Global Street Art website said officials probably don’t want to appear heavy-handed.

“It wouldn’t help uphold the commercial interests of the sponsors to persecute the artists,” he said.

Business owners who fall foul of stringent Olympic branding rules have not been so lucky. A law passed by the British government ahead of the games gives organisers the power to bar companies from using the Olympic trademarks and even certain combinations of words, such as “Higher, Faster, Stronger” and “London 2012.”

Enforcement can be stringent to the point of farce. A London diner called the Olympic Cafe was forced to change its name — it’s now the ‘Lympic — while a lingerie store in central England was told to remove a window display that used five hula hoops and some sports bras as a tribute to the Olympic rings.

Within the 500-acre (200- hectare) Olympic Park, food vendors other than sponsor McDonald’s are barred from selling french fries — except as part of the traditional supper of fish and chips. The chip ban caused outrage among staff working on the opening and closing ceremonies, who succeeded in having the rule temporarily relaxed.

Companies like McDonald’s, Coca-Cola and Samsung pay as much as $100 million each to be official sponsors during each Olympic cycle, and expect organisers to protect their rights.

The logos of rival companies are banned from Olympic Park, and from an “advertising and street trade restriction zone” around the venues.

Spectators are not immune from the restrictions. London organisers have drawn up an extensive list of forbidden items inside Olympic venues, which includes not just weapons and noisemakers but “any objects or clothing bearing political statements or overt commercial identification intended for ‘ambush marketing.’”

Even in this environment of extreme trademark vigilance, knitters are the last people one would expect to become Olympic outlaws. But that is exactly what happened to a group of woolworking enthusiasts who decided to celebrate the games with a knitting challenge called the Ravelympics.

Organisers of the contest — in which participants are challenged to complete a personal knitting project over the 17 days of the games — were shocked last month to receive a letter from lawyers for the US Olympic Committee, ordering them to rename the event because it was “disrespectful” and denigrated the name of the Olympic Games.

Donna Bowman, one of the organizers, said knitters understood the Olympic committee’s need to protect its trademarks — but were angered by the suggestion their craft competition was mocking the games.

“The cease-and-desist letter seemed to go out of its way to suggest the events we were doing — like an afghan marathon or a handspun heptathlon — were somehow jokes that were intended to parody or disrespect the Olympics,” she said. “That’s not how people feel about it at all.”

Eventually, a spirit of Olympic compromise prevailed. Organisers renamed their event the Ravellenic Games, and the Olympic Committee apologised for its heavy-handed approach.

Bowman said in their rush to judgment, Olympic authorities had missed the point of the knita- thon — people want to embrace the spirit of the games and get involved.

“People feel like the Olympics don’t just belong to (broadcaster) NBC and to the committees and the people that license stuff,” she said. “It’s a part of culture, not just a part of commerce.”