A former boarding school teacher who sexually abused a string of boys has been jailed for six and a half years.

William Bain preyed on the five children who were pupils at another private school where the 62-year-old worked at the time.

One boy was attacked after going to Bain for help because he was being bullied.

Bain, of Crieff, Perthshire, went on to secure a senior post at the £22,000-a-year Glenalmond College in Perth and Kinross.

He was finally caught last year when one victim discovered he was still teaching and called police.

Bain returned to the High Court in Glasgow after pleading guilty to five charges of using lewd and libidinous practices while employed as a teacher.

Judge Lady Scott told him the crimes were "persistent" sexual abuse and that he appeared to have no "contrition" for what he had done.

The abuse occurred between 1989 and 1995 when Bain was a teacher at a fee-paying school in Dunbartonshire and the victims were all pupils there.

The attacks occurred either in an empty classroom, a photography dark-room or at Bain's private flat at the school.

The first boy was aged 11 when the abuse started. The next victim was 12 when Bain began molesting him several times a week.

Around the same time, Bain repeatedly preyed on a third boy, who was also 11 when he was first abused.

The fourth pupil was the same age as he was abused a total of 50 times.

Prosecutor Ross McFarlane said the final victim, aged 12, had spoken to Bain to seek help as he was being bullied at the school but, instead, Bain inappropriately touched the traumatised child.

Bain left the school in 2000 and moved to the exclusive Glenalmond College.

His abuse remained unknown until 2015 when his first victim discovered Bain remained employed as a teacher and reported the ordeal he had suffered more than 20 years ago.

A large scale probe eventually resulted in the other four who were abused being traced.

An impact statement completed by one of the victims revealed the abuse had a "profound effect" on him.

Bain had also faced in court accusations that he attacked three other boys, but prosecutors accepted his not guilty pleas.

The court heard that Bain realises his reputation has been "utterly devastated" by what happened.

After the hearing last month, a spokesperson for Glenalmond said Bain had been "immediately suspended" when the accusations first arose.

The statement went on: "Police Scotland made us aware of allegations of a child protection nature made against a former member teaching staff.

"These related to his previous employment and were not in connection with Glenalmond College."

Detective Inspector Grant MacLeod, of Argyll and West Dunbartonshire Public Protection Unit, said: "Bain is a dangerous predator and it is through the courage of his victims that he has been brought to account.

"We hope this sentence will bring some closure to them and allow them to move forward with their lives.

"Police Scotland will ensure survivors of childhood sexual abuse are listened to and their reports are thoroughly investigated regardless of the passage of time."

"Police Scotland, both nationally and locally, will work with statutory partners and third sector to ensure that survivors of childhood abuse are supported through the investigation and criminal justice process.

"As the case of Bain demonstrates today, we will work tirelessly to ensure that those who perpetrate these crimes will not go undetected, irrespective of the time that has passed.

"It is never too late to report abuse and we would ask anyone with further information about William Bain or other abusers to contact Police Scotland via 101."