But the people he befriended always had children. They, seeing him as a family friend, would visit his stall after school.
Then, in December 1994, the spell broke. Alice, 13, told the police that when she had stayed at Pastel's flat one night after running away from home he offered her alcohol, masturbated himself and indecently assaulted her. Pastel denied the accusation and no charge was brought.
Six months later, social services heard that Pastel had been taking pictures of children who had visited the stall. The council called in the London Investigation Team run by the National Society for the Protection of Children to co-ordinate and conduct an inquiry for them.
The team was set up two-and-a-half years ago to help protect children from organised sexual abuse. In the last year they have seen 104 children and conducted eight investigations, of which three ended in prosecutions and convictions; one man has fled abroad and has yet to be brought to trial, in another there was not enough evidence to charge, and three are continuing.
The team comprises a manager, four social workers and administration staff. "Child pro- tection agencies were mainly focusing on abuse in families," Maureen Carson, the team manager, said. "We were set up to do something different. We were concerned that people were not recognising the organised abuse of large numbers of children."
Each case involves careful planning, in conjunction with social workers and the police. All relevant information is gathered, a strategy mapped out and interviews conducted with the children and their parents. The team also ensures that help and support is available to the families and sets up independent witness support for children required to give evidence in court.
The image of a paedophile as a man in a grubby raincoat is, one of the team says, simply not true. "They tend to be extremely well-resourced," Ms Carson agreed. "They can identify vulnerable members of the community. They can be incredibly articulate, well-respected, educated and leading a busy professional life. They work out what activities children are interested in and use them to engage their attention. They have used things like the Internet, video games, camping trips - anything children enjoy."
Children told the team how they trusted Pastel when he took pictures of them because he was a "friend" of the family. He asked several children to take part in making videos, telling one girl he would pay her pounds 150 if she did.
The investigation team has uncovered cases where paedophiles have worked by themselves and where they have worked together. They have traced contacts abroad and networks in London. In Pastel's case children revealed that he was working with another man at the market, Jeremy Smith. At Smith's house the police found child pornography and evidence linking him to another man, Ralph Tall, who lived in Gibraltar. His home was also searched and more child pornography was found, some provided by Smith.
Even when children have indicated that they are being abused, getting them to talk can be a long and painful process. The NSPCC team and social workers encourage them to speak about their experiences using fuzzy felt, small dolls and a jigsaw "body puzzle", and they provide them with therapy and counselling afterwards.
Social workers have to listen to tales where children have been encouraged to "recruit" friends or led on to abuse other children. "It is something that we all - and we are all social workers - find distressing, say when you hear about serious forms of abuse that you have not heard of before," Ms Carson said.
"Sometimes we meet young children who have been abused for a year or more. Then when they tell you their story, you find out that two or three more children are involved. What must it feel like for the parents to have to hear this? What if it is someone they've allowed to be alone with their child?"
She believes that the London Investigation Team's work is necessary to stop the repeated abuse of children. It is calculated that on average an abuser will have attempted or committed 238 offences before he is caught. "Our aim is to protect children and for that we need to get convictions. We need to stop paedophiles abusing other children. We need to stop children suffering," she said.
Even a successful investigation can leave the team feeling frustrated. Ian Pastel was eventually brought to trial after 30 children had been identified from photographs and interviewed. Last March, he was sentenced to just 12 months' jail for an act of gross indecency.
t All names and some details of cases have been changed
Anyone concerned about a child's welfare can contact the NSPCC child protection helpline anytime free on 0800 800 500.Reuse content