A driver was yesterday convicted of indecently assaulting a seven-year-old girl on a school bus. In the District Court Deputy Judge Timothy Jenkins told the defendant, 30, that he had committed an 'extremely serious and disgusting' crime. A psychiatric report obtained by the defence showed the defendant had low intelligence and that a brain disease he had suffered when he was young had affected his speech. But the judge said that although the defendant's personal situation and medical background deserved a measure of sympathy, it did not justify what he had done. In December 1995 and January this year the defendant, who could not be named in case it identified his victim, drove the girl to a quiet park where he touched her intimately three times. He will be sentenced on September 9.