How to Rile-up a Brit.

The British embassy in Madrid has a Facebook page - Brits in Spain - where it dispenses wisdom and advice.
On the Pamplona San Fermin fiestas they say. ' For anyone heading to Pamplona to run with the bulls, it´s well worth checking out the official site advice to make sure you´re fully prepped. And it´s not all about the bulls, there´s live music, fireworks. . . basically a week of partying. There´s a reason why San Fermin is on everyone´s list of top fiestas!'.
The annual fiesta in Pamplona includes  (horror alert!) bullfights and the bull-running, where for eight days, around 2,000 young people run daily with the bulls as they are herded by some cows down to the pens behind the bull-ring for that evening entertainment. Six bulls and six mansos thunder through the narrow streets leading to their destination, intermingles with enthusiastic runners - the odd one of which will do himself some injury.
They've done it for years according to Wiki, and fifteen people have managed to kill themselves in the Pamplona bull-run since 1910: thirteen Spaniards, one Mexican and one American.
Most people consider it fun, or high jinks - a bit like driving a motorbike too fast or playing truth or dare (it certainly beats jumping off a hotel balcony, irredeemably popular with British holidaymakers), but it's only the British who, generally speaking, disapprove of Pamplona's attractions.

A jolly bull-run

This is because the British, with their extraordinary exceptionalism, consider themselves better than foreigners (you don't agree? tell me more about Brexit) and to balance this, they offer a kind of cult-like worship towards all animals (perhaps, in part, to teach those same foreigners a lesson). Who but the British would instigate a massive neutering program for feral cats to subsequently return them to the wild - and raise funds for this effort? Our local group of concerned ex-pat Brits are talking about a '100km radius of fixed felines' (the vets must be doing cartwheels for joy).
The Brits like to publish fake news about bullfights (Vaseline in their eyes etc) - and they may even find a Spaniard who doesn't approve (in brutal reality, most people here don't care one way or the other). The fact is that maybe one in ten thousand bovines will be a Toro Bravo rather than a hamburger bull - doomed as it is to a short life in a pen before an abrupt passing in an abattoir at 18 months of age). But their worst criticism is against their own citizens. Our local pet charity has been run by a woman who's American husband has never missed a bullfight in fifty years. He writes about his exploits and publishes his photographs, but nobody says anything. I am invited to a bullfight every couple of years or so with my Spanish wife by our friends and I get into all kinds of trouble. One jack-ass from the same charity even managed to stop me giving a speech (to raise funds for them) on the supposedly bland subject of our local history because of my bloodthirtsy enthusiasm for what is of course a fully-legal protected national fiesta! 
Thus, the Brits in Spain Facebook page, which is answered here by 360 people (by Friday afternoon), including Christine 'Its not on my list, it should be banned its cruel for the animals and if people do not realize by now that it is also dangerous I feel sorry for them that they do not have the intelligence to know this, plus fireworks which frighten even more animals both domestic and wild animals, often frightening to death young offspring, with loud bangs that they can either hear or feel the vibration of which distresses them. the entire horror show is a disgrace', and the succinct Priscilla 'Strictly for scumbag heathens'.

A recent massive anti-toro demo in Pamplona

Here's Lesley: 'Brits in Spain should not be promoting this' and Tracey: 'Shame on you promoting this barbarity' and here's the lovely Angela: 'Let's hope a good few humans are gored to death in this barbaric display of blood thirsty morons having a fabulous time drinking and having a great time watching animals suffer. Obscene and monstrous !!'.
The normal Brit in Spain post on Facebook from the embassy will attract about five comments (unless its about dogs, where it will rise alarmingly).
As far as Pamplona is concerned, it makes a fortune from its fiestas. A recent article in the Spanish press talked of the amount of beer sold during the San Fermines. In 2017, one and a half million people visited the city over the fiestas. The likelihood of this activity being closed down (or inflatable rubber-bulls supplied in substitution) because the Brit ex-pats in Spain and their free-sheets (check The Olive Press or The Weenie) disapprove seems a little unrealistic.
We Brits like Spain well enough because it's cheap, it's warm and the food is good. We don't seem in general to show much interest in the culture of the country and, beyond our fervour for saving animals - dogs, cats, donkeys and toros - from the Spaniards, we try to involve ourselves with our neighbours as little as possible.