The tactics of a small hardcore of animal rights activists have brought them in confrontation with major corporations, scientific establishments and the government.
By Simon Cox and Richard Vadon
BBC Radio 4
Some of their strategies have appalled many people, especially those who have been targeted. Whether people support them or not, it cannot be denied that their tactics have had an impact. So what have been the key elements of their approach?
THEY HAVE 'GOT SMART'
The campaign waged against Huntingdon Life Sciences, Europe's largest vivisection laboratory, has shown the increasingly sophisticated tactics of the animal rights movement.
The Stop Huntingdon Animal Cruelty (Shac) campaign has focused on the suppliers. So far this year 80 companies have severed ties with Huntingdon because of pressure from animal rights campaigners and fear of bad publicity.
Greg Avery of the Shac campaign has found that many of the biggest companies can be persuaded very quickly and not because they care about animals.
British groups have worked abroad
"Businessmen don't care about ethics; all they care about is profit. They don't make ethical decisions; they make financial ones. So we turn it into a financial decision - we will hit you where it hurts and that's hitting you in the pocket."
THEY HAVE BECOME RELENTLESS
The key lesson that the animal rights movement has learnt is being relentless. Campaigners used to focus on a variety of local targets across Britain. But starting with the Consort kennels campaign, the movement has concentrated its fire on one national target.
Campaigner Greg Avery was involved with the Consort campaign and says: "We grabbed hold of those kennels and didn't let go. You don't pick a company unless you can close it down because otherwise you just make those companies stronger. So when they are chosen - they are finished."
THEY BELIEVE INTIMIDATION WORKS
For all of the sophistication of the movement they are well aware that if arguments and legal pressure fail there is always illegal intimidation. The Shac campaign says it is against all such tactics but some nasty things have happened to companies it has named and shamed on its website.
For instance, on 10 September 2004 fake bombs were planted under the cars of two directors of Northgate, a supplier to Huntingdon. Later that day, Northgate announced that it had terminated its business relationship with Huntingdon Life Sciences.
Companies connected to Huntingdon have this month alone been the subject of attacks, including damage to cars, homes being daubed with paint, and windows being smashed. One family which breeds animals for research has suffered a consistent campaign of harassment.
Shac has denied any involvement in these incidents and while these tactics are widely condemned, they nevertheless are successful in persuading companies to accede to the campaigners' demands.
The Home Office has funded a National Extremism Tactical Co-ordination Unit within the Association of Chief Police Officers, which aims to share information across the country about the best ways of tackling illegal activities.
New laws to stop extremists protesting outside people's houses are also planned.
THEY HAVE 'GONE GLOBAL'
The British animal rights movement is the largest and the strongest in the world. Activists across the globe now look to the UK to learn how to campaign more effectively.
Patti Strand of the American Lobby group the National Animal Alliance believes the British have a lot to answer for.
"We view the United Kingdom as the Afghanistan for the growth of animal rights extremism throughout the world. The animal rights movement that we are dealing with in the United States is a direct import from the United Kingdom."
THEY HAVE PLANNED FOR THE FUTURE
Such is the confidence of the animal rights movement that they are already thinking about the future. Greg Avery of Shac has new targets in his sights.
"When Huntingdon closes we won't just go on to another company. We will go on to a whole area of animal abuse. And look to knock out big chunks - puppy farming, factory farming, circuses and zoos. All these could be finished. We're becoming bigger, even more intelligent and even more determined not just to take companies down but to finish whole areas of animal abuse."
Revered thinkers within the movement like Ronnie Lee, founder of the Animal Liberation Front, want to go much further than closing down zoos and circuses.
"To create a world that is fair to the other creatures on it we have to have some policy of reducing the human population so that would mean we would have to breed less."
Most campaigning is within the law
How much less? Lee says a reduction in the British population from the current level of 60 million to just 6 million would be better for the animals. Lee is serious enough about reducing the population to have had a vasectomy.
His views aren't ones you'll hear at the stalls campaigning against animal cruelty all over Britain but what's clear is that animal rights activists won't be content with shutting down fur farms or animal testing labs.
Buoyed by their success they want nothing less than to change the world.
Battle for Influence: Animal Rights is broadcast on Radio 4 on Thursday 18 November at 2000 GMT.