A teacher who asked pupils to undress in order to measure their genitals has been banned indefinitely from teaching.
Denis Hays, 72, was teaching at Greasbrough Primary School, Rotherham, when he invited pupils to his home for inspections between 1975 and 1977.
He was dismissed in 2015 when claims emerged that three pupils, aged between 11 and 14, had taken part part in his so-called "child development study".
A disciplinary panel found Mr Hays' behaviour was sexually motivated.
Giving evidence to the panel, one of the boys, Pupil A, described how Mr Hays had measured each of the boys' various body parts.
He said this included measuring his and Pupil B and C's head, arms, legs, neck, chest, penis and testicles, while the boys were naked.
The three pupils attended Mr Hays' home once every three months over the two-year period having recently left the primary school, The National College for Teaching and Leadership panel heard in March.
Neither the primary school nor the boys' secondary school was aware of the study.
'Study was inappropriate'
Mr Hays had been teaching at the school for 46 years when he was dismissed for gross misconduct in 2015 after Pupil A reported the allegations.
He claimed the private study was designed to help him gain further qualifications and promotion, but no such study was ever completed.
The panel rejected the teacher's claim that he did not grasp the seriousness of his conduct and that he was merely "naive" .
It said in its report: "The panel considers that, on balance, Mr Hays was intentionally trying to keep a true account of the study from others in the knowledge that the study was inappropriate."
Mr Hays claimed he had parental permission for the boys to participate in the study, but the panel heard the parents were unaware of what the measurements involved and that Mr Hays was often the only adult present during the examinations.