A teacher who throttled his headmaster after being sacked for chasing a colleague with a pair of scissors in a staff meeting was jailed indefinitely.

Arek Bielecki, 33, brandished the scissors at Monteagle Primary School in Dagenham, Essex, before head-butting fellow teacher Michael Thompson.

After being dismissed, the ponytailed Pole – who has no teaching qualifications – returned to the school, locking himself in with head Nicholas Munns, 57, snarling: ‘I will kill you’.

Staff watched in horror as raging Bielecki strangled bespectacled Mr Munns, who was ‘turning blue’ before brave teaching assistant Caroline Lowe barged into the office to rescue her boss.

Mrs Lowe had to ‘prise’ Bielecki’s fingers from Mr Munn’s throat while school receptionist Elaine Ward desperately fought to drag him off the headteacher.

A jury at Snaresbrook Crown Court convicted Bielecki of the attacks on Mr Thompson and Mr Munns after after a six-day trial in June.

Judge Louise Kamill, handing Bielecki an indeterminate sentence of imprisonment for public protection, said: ‘I am myself quite satisfied that you pose a significant risk to the public of serious harm by your committing further specified offences.’

The judge set a minimum of two years and three months before Bielecki can apply for parole.

But Judge Kamill said Bielecki would only ever be released ‘if and when the parole board deem it safe’.

‘There were two separate occasions when you inflicted harm on peaceable teachers,’ said the judge.

‘You continue to deny the offences and indeed maintain that the staff from the headmaster down to the administrative staff were lying about you.

‘I conclude therefore, I have no way of assessing when you may be safe to release.’

In a statement, recalling the moment Bielecki was strangling him, Mr Munns said: ‘I thought after 19 years as a headmaster, this is how it ends – on the floor of my office.’

Judge Kamill, referring to the statement, said: ‘He’s asking himself, why after 19 years of trying to do the right thing, he was subjected to that by a teacher.’

Bielecki first struck on January 4 this year after colleagues including Mr Thompson asked him to stop interrupting during a meeting chaired by deputy head Mark Austin.

The Pole, who taught youngsters a variety of subjects, claimed Mr Austin had ignored his pleas for extra stationery for an entire term.

Prosecutor Michelle Fawcett said ‘The defendant abruptly stood up from where he had been sitting, went over to a desk six to eight feet away and picked up a pair of large-bladed scissors.

‘He held them in his hand making a fist with the blades sticking out of the bottom of that fist and raised it at head height and ran at Mr Thompson.’

Bielecki only returned the blades to their pot after women members of staff shrieked in terror, but he flipped again moments later.

‘Mr Bielecki immediately brought his head back and thrust it forward again, head-butting Mr Thompson across the nose,’ said Miss Fawcett.

Mrs Ward and Mrs Lowe described how Bielecki returned to the school on March 12 after being sacked and requested a meeting with Mr Munns.

Mrs Lowe said she rushed to Mr Munns’ office after fellow staff member Sonia Gunning reported ‘gurgling and choking noises’ coming from behind the closed door.

‘I looked through the window, it was a glass panel down the centre, and I could see that Mr Bielecki was sort of bending over Mr Munns.

‘I barged at the door and I got in.’

Mrs Lowe said she screamed: ‘Arek, get off him, get off him’, adding: ‘I noticed that Mr Bielecki’s hands were around Mr Munns’ neck.

‘Mr Bielecki was strangling Mr Munns.

‘I was trying to prise his fingers to try to bend them off his neck.’

Bielecki admitted brandishing scissors at the January 4 meeting and claimed he head-butted Mr Thompson in self-defence after feeling ‘threatened’.

He denied throttling Mr Munns, claiming the headmaster had a fit during their meeting in his office.

Bielecki, wearing a Sex Pistols T-shirt, told jurors: ‘He went all red and started to screech.

‘He made some kind of coughing noise initially.

‘Then he was screaming, becoming more guttural – he began to bang on the wall.’

Bielecki, of Gosfield Road, Dagenham, denied affray, two charges of actual bodily harm and making a threat to kill but was convicted by the jury.