Although other staff members witnessed their mistreatment, the children's tormentor for some time 'got away with it', the children's counsel, Elizabeth Gumbel, told London's High Court.
Charges relating to another alleged victim - a blind child with severe communication difficulties - were left on the court file and an inquiry later confirmed the worst fears about the man's activities.
West Sussex CC, who managed the school, which also cannot be named, settled the five cases for a total of £122,500 in damages after making a full admission of liability.
Miss Gumbel said the support assistant had a prior history of psychiatric problems and the judge who jailed him said he should 'never have been employed' at a school caring for such seriously disabled children.
Other staff members had noticed his inappropriate sexual behaviour towards pupils and his quick temper.
He had, in front of colleagues, been 'physically violent' to his charges and, on occasions, had thrown helpless pupils' heads against the side of a hydrotherapy pool.
Mr Gumbel told Mr Justice Keith: 'Unfortuneately his behaviour was not reported to the authorities as promptly as it might have been.
'He seemed unafraid to carry out abuse in front of other people and appears to have got away with it for some time'.
All the victims had learning disabilities of varying degrees of severity - some of them had chromosome disorders with 'very very grave consequences', said Miss Gumbel.
And she told the judge the very fact of their disabilities had landed the police and prosecution with an up hill task in proving the charges laid against their abuser.
Approving the settlement, Mr Justice Keith said: 'These must have been troubling times for the five claimants and their families.
'I hope the end of that now this litigation has come to an end everyone can now move on.'
STRAND NEWS SERVICE