A SCHOOL teacher who sexually abused private school pupils more than 30 years ago must accept his "very substantial" jail term, top judges have ruled.

Jonathan Philip O'Brien, 57, subjected boys aged 10 to 16 to his vile advances while working as a teacher in Worcestershire and Oxfordshire in the 1980s.

O'Brien, of Fairfield Road, Bosham, near Chichester, was caged for 13 years at Chichester Crown Court in May, last year after he was found guilty of 15 counts of indecent assault.

Today, three senior judges at London's Appeal Court rejected a sentence challenge by the disgraced sir, saying his jail term was certainly not manifestly excessive.

Mrs Justice Swift said O'Brien was a teacher at private Winterfold House School, near Kidderminster, when he would lure pupils to a photographic darkroom and sexually abuse them.

Later he joined another private school, The Oratory, in South Oxfordshire, and continued his "shameful" exploitation for several years. In all, he abused nine boys.

The appeal judge said O'Brien would "exploit" the loneliness of some pupils, plying others with alcohol and cigarettes and showing them pornographic films.

He would also make those who were religious "swear on the Bible" not to tell.

O'Brien was forced to leave The Oratory in the late 1980s after one of his victims complained to the school.

However, his crimes never fully came to light until February, 2013, when one of the victims told police.

The paedophile, who set up his own business and married in the intervening years, denied any wrongdoing but was convicted.

Jurors also found him guilty of five counts of gross indecency with a child, however, those convictions were later quashed by the Court of Appeal.

O'Brien continues to deny any wrongdoing, shows no remose and claims he is the "innocent victim of a conspiracy".

On appeal, O'Brien's barrister, David Whittaker, today argued that the13-year jail term was "manifestly excessive".

He said the judge failed to give proper weight to O'Brien's mitigation, including his lack of offending since the abuse.

But Mrs Justice Swift, sitting with Lord Justice Pitchford and Judge Paul Batty QC, said: "We consider the judge was right to say that 'a graver abuse of trust is difficult to imagine'.

"The total sentence is indeed very substantial, but rightly so, we consider, given the particular circumstances of this case.

"We are satisfied that the total sentence of 13 years reflects the seriousness of these offences and cannot be regarded as manifestly excessive."

The appeal judge also rejected a bid by O'Brien to challenge to the terms of a sexual offences prevention order (SOPO) which bar him from having contact with children after his release.

O'Brien claimed the SOPO was "disproportionate". But Mrs Justice Swift said the order was necessary to protect children from O'Brien in the future.