'Every campaign needs a victory and this will reinvigorate ours'

Espousing peaceful means, although reluctant to condemn animal rights violence, their protests are channelled through legal organisations which are closely monitored by the police.

Although each group is focused on a single issue, they coalesce around high-profile targets, coming together as in the case of the Darley Oaks Farm campaign.

Typical is Greg Avery, founder of Stop Huntingdon Animal Cruelty (Shac) which has waged war against the medical research company in Cambridgeshire since 1999. Targeting of suppliers and business associates has resulted in more than 100 companies from taxi firms to major hauliers cutting ties with Huntingdon Life Sciences.

Mr Avery has explained his philosophy as: "The Nazis could not have operated Auschwitz without suppliers. Neither can companies."

In 2002, the former tailor was sentenced to six months in jail for conspiring to cause a public nuisance. He previously served four months after pleading guilty to breaching the Public Order Act. In November 1998, he was sentenced to two weeks in jail for assaulting a policeman. He spent 18 months on remand in 1996 after police found 100 incendiary devices in the Birmingham house where he was staying. He was later acquitted.

Robert Cogswell, the 39-year-old son of a banker, was the driving force behind the successful campaign to stop the construction of a primate research centre in Cambridge in 2004. His organisation, Stop Primate Experiments at Cambridge (Speac),now renamed Speak, is battling to prevent the building of an animal research centre at the University of Oxford. Yesterday he urged activists to turn their energy to other campaigns.

"Every campaign movement needs a victory and this should reinvigorate the animal rights movement," he said.

Speak recently widened its campaign against Oxford to target charitable organisations that provide funds to the colleges.

But the organisation which lurks in the shadows and the one routinely blamed for violence is the Animal Liberation Front (ALF). It was founded in the UK in the 1970s by Ronnie Lee, a former trainee solicitor, who served three years in jail for arson offences. The ALF and the Animal Rights Militia typically claim responsibility for their actions anonymously on the internet under the slogan "til all are free".