In 1975 a young philosopher named Peter Singer published a book with the provocative title Animal Liberation, arguing that dumb beasts should be given some of the same rights as humans. It sold half a million copies and kick-started the animal rights movement.

Thirty years on an alarming escalation in animal rights activism dominates the headlines. A farm breeding guinea pigs in Staffordshire capitulates to six years of intimidation, including the desecration of a family grave. Amid campaigns by arsonists to block research laboratories, new laws threaten jail for economic sabotage.

What sort of monster has Singer created? Polite and the embodiment of reason, the 58-year-old professor of bioethics at Princeton University issues a weary disclaimer in the accent of his native Melbourne.

“I never regret having written Animal Liberation and having contributed to the animal movement,” he says. “Although I would want to disassociate myself from some elements of that movement, they are a very small element and on the whole I think the movement has done an immense amount of good.”

Tell that to people who have been firebombed, I suggest. He demurs: any movement of a certain size will attract people who are “a bit fanatical” but “you’re never going to agree with all of them”.

He does not get off the hook so lightly. Surely he bears some responsibility for providing the intellectual ballast to what is being compared to a terrorist campaign? He looks mildly irritated. “I mean, you can’t help that, right? You may have opposed apartheid in South Africa and yet you may not have accepted that terrorist tactics be used. But that doesn’t in any way invalidate the case you make.”

Appropriately, we meet in Oxford, where Singer’s crusade began in the late 1960s amid the ferment of the anti-Vietnam demos and the music of Bob Dylan, the Beatles and the Stones. One evening Singer, on a scholarship from the Melbourne University, accompanied a fellow student to Balliol College’s dining hall, where his companion, a vegetarian, declined some meat sauce on his spaghetti. The moral implications of eating animals began to revolve in Singer’s mind.

He had never been an animal lover, although he admits to once owning a cat called Max. Such “sentimental or emotional” attachments were not necessary in order to campaign for their rights, he believes. “It reminds me of the civil rights movement in the 1960s, when people campaigning for black people were called ‘nigger lovers’,” he told The Australian Magazine earlier this year. “Those campaigners did not necessarily think black people were great. They were just outraged at injustice.”

But it was a purely intellectual exercise in his case? “Absolutely.” He credits Britain with a long tradition of caring for animals, which made people receptive to his message. The ethical issues were virtually ignored until Singer wrote an essay entitled Animal Liberation for The New York Review of Books in 1973, followed two years later by his bestselling book.

He argued against “speciesism”, the notion that it was justifiable to ignore the interests of another being merely because it was not human. He was not saying that all the interests of humans and animals should be given equal weight, but where they had similar interests, such as avoiding physical pain, those were to be counted equally.

He rejects the sobriquet “father of animal rights” in favour of midwife and credits other philosophers with assisting the labour. “Previously (protests against animal testing) had been pitched at animal lovers and most of the literature was based on pictures of puppies and kittens being experimented on. The philosophers helped to break out beyond that so that it became a moral and political issue, like racism, sexism or gay liberation.”

Singer went on to achieve even greater recognition with Practical Ethics, which remains one of the most widely used texts in applied ethics. His studies of famine relief, euthanasia and bioethics has earned him Time magazine’s accolade this year as one of the top thinkers of our time. He donates a fifth of his salary to Oxfam and the animal rights movement.

I have caught Singer on a brief visit to Britain and bring him up to speed with events at Huntingdon Life Sciences (HLS), the Cambridgeshire research laboratory which activists are targeting through suppliers and shareholders. Arsonists have pledged to attack anyone they perceive as having links with the company.