Professor William Friedrich, a consultant at the Mayo Clinic in Rochester in the USA, said his clinical practice focused on assessing and treating maltreated and traumatized children. He estimated he dealt with up to 160 children a year.
The council and team are being sued for libel by former nursery workers Christopher Lillie and Dawn Reed.
In its 1998 report, the team concluded Mr Lillie and Ms Reed had sexually, physically and emotionally abused children from Shieldfield. Four years earlier they had been acquitted of indecently assaulting children from the nursery.
In his report before the court, Prof Friedrich said he had reviewed the material related to the Shieldfield case, focusing on the disclosures made by the children.
'One of the most compelling features of the disclosures of many of these children is that their verbal statements were often accompanied by physical behaviour that reflected their distress or imitated what had happened to them,' he said.
'It is my clinical impression, based on a review of the documents and video tapes provided to me, in combination with my experience in the evaluation and interviewing of very young children, that the majority of the evidence points to sexual abuse of these 28 children.
'I believe that the abuse onset can be tied to their entry to the Shieldfield nursery and the weight of the evidence indicates that the perpetrators were Lillie and Reed.'
He said the nursery did not invite parent involvement and oversight and was ran too closed a system.
'The director remained in her office and provided insufficient monitoring of her staff and the whereabouts of these children,' he said.
'A review of the minimal biographical information that I have available to me on Lillie and Reed, in combination with parent reports, indicate that both of these people had an elevated risk for the maltreatment of children.'
He said Mr Lillie had a disrupted history of close relationships, lost his mother when he was young, lived outside of his family before the age of maturity, and had a criminal history.
'He was also reported to be socially uncomfortable with adults,' he said.
'Reed was cruel to these children in her discipline and statements, and grew up without a father, and raised in a family whose organisation contributes to the risk of sexual abuse.'
He is continuing his evidence.
STRAND NEWS SERVICE