Richard Groome, 80, who worked in senior positions in care and educational settings around England, has been convicted by a jury of three sexual offences against a boy he was supposed to care for in his role at a boarding school in south Shropshire.
The jury deliberated at Shrewsbury Crown Court for less than three hours on Friday before finding Groome guilty of two charges of indecent assault as well as another serious sexual offence, all against the same schoolboy.
Groome, now of Oxford Terrace in Bath, faces a jail term – he will be sentenced on May 13.
The trial heard from police interviews and complaints lodged against Groome, and witnesses were questioned by prosecutor Graham Russell.
After the jury delivered its verdicts, Judge Anthony Lowe told Groome: "As I'm sure you know, there is only one sentence I can impose – a prison sentence.
"But the length of that sentence is something I am going to have to give some detailed thought to."
He granted the defendant bail for two weeks so he can "get his affairs in order".
The judge thanked the jury for their time and diligence, saying: "You are the cornerstone of our criminal justice system."