The footage showing Millar drawing on the boy’s face was played to the court and a woman, described as management, was seen to walk past.

In a statement read to the court, the victim said he had been “embarrassed” in front of his classmates.

Judge Hatton said: “It would be obvious to anyone that your conduct was hideously inappropriate and nothing short of cruel bullying.

“You were clearly in a position of trust. One case involved you drawing a penis onto the face of a pupil.

“That involved gratuitous degradation of your victim.”

He put two pupils into headlocks and also feigned a punch and kick at one of them, the court heard.