An award-winning teacher who hid behind a trusted classroom reputation while grooming and sexually abusing 12 pupils has been jailed for four years.

Martin Gallacher, 46, preyed on boys at Paisley Grammar School between 2015 and 2024 — exploiting the very children he was supposed to protect.

To colleagues, the computing teacher appeared dedicated and talented. He even received a “best teacher” award.

Behind that image, he was exploiting vulnerable teenagers during lessons, school clubs and football coaching.

At Paisley Sheriff Court, Sheriff Eoin McGinty described his crimes as a profound betrayal of the trust placed in teachers by children and their parents.

The sheriff said Gallacher abused boys in the classroom, concealing his actions behind his desk and “hiding in plain sight”.

The damage was devastating. One victim considered taking his own life because of the trauma.

Gallacher targeted pupils during lessons and when they were alone. He also used his involvement in a lunchtime club, badminton club and school football team to gain access to boys.

He contacted some through PlayStation, Discord, Steam and Snapchat, and gave some gifts and money.

His offending included sexual touching and performing sexual acts on pupils.

Gallacher, of Paisley, Renfrewshire, denied wrongdoing, claiming his contact with the boys had been innocent. A jury rejected his account and convicted him.

The sheriff told him: “This was serious sexual offending committed on your pupils.”

He also condemned Gallacher’s exploitation of a particularly vulnerable victim and said his crimes had cast a shadow over fellow teachers.

The abuse was exposed because a pupil found the courage to speak out.

The sheriff praised the first boy to report what had happened, along with his mother’s determination, saying Gallacher would in all likelihood have continued offending without their actions.

Gallacher continued to deny his crimes and showed no emotion as he was sentenced.

Alongside his four-year prison term, he was placed on the Sex Offenders’ Register for life.

A 10-year Sexual Harm Prevention Order will restrict his activities, including online activity, after release.

He also received a 10-year Non-Harassment Order, banning him from approaching or contacting any of his victims.