Horsemeat has been found in beefburgers on sale in UK and Irish Republic supermarkets. But why do the British have such a revulsion over the idea of eating horsemeat?
The discovery of horse DNA in burgers in major supermarkets such as Tesco and Iceland has been met with alarm among consumers.
Horse-eating, or hippophagy, spread in Europe in the 19th Century, after famines caused several governments to license horse butcheries.
The meat is still commonly consumed in France and Belgium, as well as parts of Central Asia and South America.
So why are the British so squeamish about eating horse?
There is no real logic as to why plenty of Britons are perfectly willing to eat cows, pigs, and chickens, but see horses as taboo, according to Dr Roger Mugford, an animal psychologist who runs the Animal Behaviour Centre.
"I'm a farmer and there is an irony. Why are horses different from pigs and lambs?" he says.
Part of the reason is people frequently see horses as pets, and humans tend to put "extra qualities and values" on animals they call pets, he says.
"As soon as you give an animal a name, how can you eat it? I've got lambs, sheep, with names - they live forever. I don't name the commercial flock, which won't," he says.
History is also responsible for attitudes towards horses, according to Mugford.
"Horses helped out in warfare. There have been huge sacrifices alongside riders in historic battles. And there are sentimental depictions like War Horse," he says.
Their widespread use as working animals has had a lasting effect, argues food historian Ivan Day.
"We have to remember at one point, before railways, horses were the main means of transport. You don't eat your Aston Martin," he says.
Food historian Dr Annie Gray agrees the primary reasons for not eating horses were "their usefulness as beast of burden, and their association with poor or horrid conditions of living".
She suspects the practical considerations have become so embedded in culinary norms that horseflesh has garnered emotional connotations.
But all of the above reasons apply as much to France as they do to the UK. There must be more to it.
"It enables us to have yet another point of difference with the French," says Gray.
"Beef has long been symbolic of Englishness and therefore anything we can do or say to put British beef on a pedestal is usually done - ergo the thought that the French eat horse while we eat good beef becomes a chauvinistic way of asserting national identity," she says.
Gray, who lived in France for three years, says for her, it is completely natural to eat horsemeat as it was sold at her local butcher.
"I am far more concerned with where the food is from. I would far rather eat ethically sourced, well-cared for horse, than battery chicken, for example," she says.
So are attitudes changing at all?
Peta says the thought of unexpectedly tucking into a horse burger has "rightly shocked the nation". But it says Britons who say "neigh" to horsemeat do so only because they find ponies "cute".
"Why is one species cherished while another is spurned? If this story has shocked people, they should consider leaving all flesh off their plates and going vegan," it says.
Rather than seeing them as "cute", others may be more inclined to think of horses as majestic, or associate them with nobility.
The killing of horses for meat is still an emotive subject as many people see them as companion animals rather than a food source, according to the RSPCA.
But the proliferation of horsemeat jokes on Twitter suggests other people are seeing the lighter side of the story.