ANIMAL rights extremists are stepping up their campaign of terror against the head of a centre which sells monkeys to medical research laboratories.

The woman, a former vet who has asked not to be named, had her car fire-bombed last week. She has previously been attacked at home on many occasions and had a hearse sent to her house after a local undertaker was told she was dead.

Last week while she, her husband and their 12-year-old son slept at home in a quiet street in Sussex, arsonists broke into the garage and torched their two cars. "At first it was hate mail sent to work; disgusting and unpleasant messages, but you could throw it away," she said. "But then the attacks on me and my family started at my home. I worry most about my son. These people are frightening."

Sussex Police are treating the latest incident as arson. They are investigating members of the Animal Liberation Front and supporters of the Save The Shamrock Monkeys campaign. The campaign started in April last year when 25 men and women, carrying bricks and wearing balaclavas, smashed the front and side windows of her house and their cars.

"My son was there," she said. "We were all frightened - though with me it was accompanied by a sense of disbelief that I could be targeted for simply doing my job."

The second incident took place at their new home last summer, a few months later. A car was spray-painted and vandalised. Then the replacement hire car had its tyres slashed and windows smashed. Shortly after the terrorists sprayed the back fence of the couple's property. The message read: "Monkey Killer You Will Pay".

At the same time an increasing number of threatening letters were being sent to Shamrock staff. One of them contained razor blades. By October terrorist attacks had also started at the homes of some of Jane's key workers. "On Hallowe'en night about 50 of them turned up at our house, and sprayed paint on the house and the walls as they shouted obscenities and abuse," she said.

"The same night they visited two other staff homes. But we foolishly opened the front door to reason with them. It was a big mistake." The glimpse of the couple gave the terrorists the chance to take photographs, which they made up into "Wanted" posters and pinned on lampposts throughout the neighbourhood. At Christmas and New Year the incidents became most fierce. Frequent attacks at their home left her and three of her staff with boarded up windows, throughout the holiday.

Two weeks later, as she drove through the electronically-controlled gates into her garage, she was set upon by four thugs with sledgehammers who smashed the front, side and back windows of her car. She said: "I couldn't think what to do. I suppose I was hysterical."

The latest attack has left her even more frightened. but determined to carry on her work. "If I leave someone else will inherit the trouble at Shamrock. I simply do not see why that should happen."

The woman is the head of Shamrock (GB) Ltd - a monkey quarantine centre set up in the Fifties that helped to develop the polio vaccine. Today the animals, most of them macaques purpose- bred in Mauritius, go on to laboratories for research on diseases such as Alzheimer's, cystic fibrosis, and Parkinson's.

The woman has worked at the centre since 1984, first as a senior vet then rising to become managing director last year. She prides herself on providing good care for her primate charges but knows that some people find research on animals distasteful. What angers her most, however, is their refusal to listen to the truth.

A perfect example of what she regards as the hypocrisy of the animal rights movement occurred recently, when a protester at the site fell and needed hospital treatment. It turned out that he needed a hip replacement. "Those replacement techniques involved a lot of pioneering research on animals," she said. "Did he refuse the treatment? Of course not."