A 16-year-old schoolboy who stabbed a teacher in the head after asking her to check his homework has been locked up for four and a half years.

The teenager, who cannot be named for legal reasons, attacked history teacher Vicki Williams ‘out of nowhere’ at a secondary school in Pembrokeshire in February.

The defendant, who was 15 at the time, waited until the end of the school day when Ms Williams was alone in a classroom before pulling a knife from his rucksack and bringing it down on her skull.

He was found guilty of wounding with intent after being acquitted by a jury of attempted murder at Swansea Crown Court.

Ms Williams said she saw ‘pure hatred’ in the boy’s eyes after he thrust the kitchen knife with an eight-inch blade towards her and pushed her into a chair before fleeing.

Children were placed into lockdown following the attack at Milford Haven School.

Ms Williams watched the sentencing hearing from an online link but in a victim impact statement said she had been suffering from post-traumatic stress disorder.

She said she did not know if she would be able to return to teaching.

Passing sentence, Judge Paul Thomas KC said it was ‘pure luck’ Ms Williams had not been seriously injured or worse.

He said the boy had an undisclosed issue with the history teacher and bore her ‘considerable ill will’.

‘I don’t know why you attacked Ms Williams with that knife, you never told anybody why you did it,’ the judge said.

‘I think it may have been that in some way she had upset you, but I don’t know for certain why.

‘What I do know for certain is that you took a knife that day to school because you wanted to really hurt her with it.’

In a police interview, Ms Williams said the boy came to her classroom ‘cool and collected’ at the end of the school day to ask if his ‘work was correct’.

She said that ‘confused’ her because he had ‘never seemed bothered before’.

Ms Williams said ‘alarm bells’ rang in her head when he shut the classroom door, saying it was cold.

She said he was trying to ‘keep her talking’ while he tried ‘to find something in his bag’.

‘I ask him again, “are you sure you’re alright?”. And then he pulls [the knife] out of the bag and lunges at me,’ she said.

Jurors heard the boy pulled a large kitchen knife from his bag and struck her in the head before a ‘violent struggle’ ensued during which Ms Williams tried to take the weapon from him.

She said the attack came ‘out of nowhere’.

The boy then ran from the school while the teacher was taken to hospital in Haverfordwest, where she was treated for a wound to her scalp, scratches on her back and minor cuts on her hands.

Christopher Rees KC, prosecuting, said: ‘The prosecution case was that he had deliberately brought a knife into school in order to attack Vicki Williams.

‘It was a carefully planned attack. He waited until Vicki Williams was alone in her classroom after the school day had concluded.’

During the trial Matthew Roberts KC, defending, suggested the pupil had taken the knife to school to ‘show off’ to other boys.

The defendant previously pleaded guilty to possessing a kitchen knife on school grounds.

The judge said the defendant had never shown any remorse for what he had done and the court had a duty to protect teachers.

‘The courts have to try to keep teachers safe from attacks on them by pupils,’ he said.

‘This is the second case of a school pupil stabbing a teacher in school in the same Welsh county in the last couple of years.

‘I want anyone who is ever thinking in the future of doing the same to know what will happen to them if they do.

‘They will spend a lot of their teenage years and perhaps beyond unable to go out with their friends, go and do what they want, go on holidays, have fun, be with their parents, follow their hobbies, and do what the rest of their friends are doing.

‘That is what happens, and that is what’s going to happen to you – the people who attack teachers with knives.’

Jonathan Pritchard of the CPS said after today’s sentencing hearing: ‘This was a shocking display of violence on a teacher doing their job.

‘Knives cause terrible injuries which can often end in fatal consequences.

‘The teacher showed great courage in what must have been a terrifying incident.

‘The strong evidence presented by the CPS resulted in these convictions which we hope provide some comfort to the victim of this awful attack.’