Mike Robins is a man redeemed. Thanks to pioneering surgery, the debilitating effects of Parkinson's disease that were wrecking his life are now under tight control.

With the flick of a switch, he can turn off the uncontrollable tremors that stopped him holding down a job, having a social life or even getting to sleep. Not surprisingly, Robins reckons he is lucky to be fit and alive. Others are not so sure.

At a recent public meeting to discuss a proposed animal research centre in Oxford, 63-year-old Robins was jeered and ridiculed when he tried to show how surgery, perfected through animal experiments, had transformed his life.

'I was bayed at,' said Robins, a retired naval engineer from Southampton. 'Several hundred people were shouting. Some called out "Nazi!", "bastard!" and "Why don't you roll over and die!" I tried to speak, but was shouted down. It was utterly terrifying.'

The attack has shocked even hardened observers of vivisection debates. 'I have seen many unpleasant things at these debates, but to scream at a middle-aged man with Parkinson's disease and then tell him he deserved to die is the worst I have observed,' said Simon Festing, director of the Research Defence Society, which defends the scientific use of animals for experimentation.

The attack on Robins reveals the gulf now separating scientists who carry out animal experiments and opponents who believe they are immoral, an entrench ment that forms the background to the publication next week of a Nuffield Council for Bioethics report on animal experiments. Its authors, made up of supporters and opponents of the experiments, has established that both sides have legitimate ethical grounds for their beliefs. Their report will also attempt to highlight methods that might help each side understand the other's arguments. The attack on Robins demonstrates how difficult that task will be.

'I wanted people to see how a person can benefit from animal experiments,' said the Oxford surgeon Tipu Aziz who operated on Robins and spoke at the debate. 'That is why I asked Mike to appear at the debate. I am now very sorry I put him through that horrible ordeal. To these people, Mike's existence is a refutation of their core beliefs. They say animal experiments do no good. Then Mike stands up, switches his tremors on and off, and their arguments are blown away. That's why they shouted him down.'

Before his illness, Robins, a retired businessman, admits he was suspicious of animal experiments. Then he developed a tremor in his right hand. Doctors diagnosed stress. Only months later did he find he had Parkinson's disease, a condition affecting one in 100 people over 60, that causes tremors, facial paralysis and eventually severe physical disability. His tremors worsened and his speech became slurred. Robins, who is married with four children, was given L-dopa, but found, as others have done, it had no effect.

Robins's life continued to disintegrate. 'It was difficult to walk. I couldn't go to the pub or restaurant. My right hand was bouncing all over the place. I got very depressed. Even my family found it hard to be with me.'

Then Mike heard about research in which Parkinson's had been induced in macaque monkeys and controlled by drilling into their brains to destroy their subthalamic nuclei, the brain centre responsible for the disease. Aziz transferred this knowledge to humans and learnt how to drill into patients' brains, fit electrodes to their subthalamic nuclei and switch off their tremors.

'However, you have to remain conscious during the operation to help the surgeon guide the electrode,' said Robins. 'That puts some people off.' But not Robins. He had his brain opened up and an electrode inserted into his cortex. 'Finally it touched the nucleus and my tremors stopped instantly.'

Now Robins has a panel sewn into his chest and uses a gadget like a TV remote to control his symptoms. When Robins switches the current on his incapacitating symptoms - waving right hand and shaking right leg - disappear instantly. It was this striking demonstration of medical science that Robins hoped to give last month but was blocked because the meeting had been packed by anti-vivisectionists. 'I want to show them what had been done for me but found myself in a room full of 250 people who were baying for my blood. The venom was horrific.'

After trying, unsuccessfully, to show how his implant worked, Robins sat down. 'A handful of middle-aged women, the type you would meet in Sainsbury's every day, were sitting behind me. They started hissing in my ear: "You Nazi bastard. That's what they did in concentration camps".'

Women like these form the core of the animal rights campaign, says Simon Festing. 'They are often well-dressed and middle-class, but are religious in their fanaticism... Accusing opponents of being Nazis is also a common tactic.' Robins tried again to speak but was drowned out.

'It was if there had been a signal to shout me down. It was terrifying. On the other hand, I am not going to be silenced. Previous generations have had to go into war and be terrified before going into action. So just because I am being frightened by these activists is not a good enough excuse not to speak out. I will do this again.'