At the centre of the claims was a 15-yearold boy with attention deficit hyperactivity disorder, who should have been in lessons when he was caught smoking outside the school’s front entrance.

In a videotaped interview he claimed Mrs Ritchie-Fallon had shouted at him and ripped his pink earmuffs from his head. He claimed she then slapped him round the face when he refused to put out the cigarette and ordered him off the premises.

Mrs Ritchie-Fallon, who has previously been kicked and punched by pupils, has always denied the claims, saying she had dealt with the situation calmly.

“I had not lost my temper or self control,”

she said.

“When I removed his earmuffs, he took another puff and I thought he had no intention of putting it out. When he took the cigarette out of his mouth, I knocked it out of his hand at waist level. The cigarette fell to the ground and I trod on it.”

She added: “He came very close to my face and started shouting. I can’t recall what he said. I asked him to leave the premises and go home.”

Giving evidence against his head teacher, a 15-year-old pupil said: “I was smoking weed then, my brain was a mash. I did not have a 100 per cent view or a 100 per cent recollection.”

A girl from the school lost her temper with defence counsel and swore when asked why she had changed her story.

Magistrates in Southampton found Mrs Ritchie-Fallon not guilty yesterday after deciding they could not say “beyond reasonable doubt” whether an assault had taken place.

Walking free from court, Mrs Ritchie-Fallon, from Long Close, Pennington, said: “I am very pleased it’s all over. It’s been a very long 11 months.” Asked if she had been confident about being cleared, she said: “I have always been confident because I knew I was telling the truth.”

But despite walking free from court, it is far from over for Mrs Ritchie-Fallon, who will remain suspended until an internal review is conducted next month.