The headteacher of a Wandsworth school where a pupil suffered multiple stab wounds during a terrifying playground attack has spoken of his disappointment that no one was convicted of attempted murder.

The 16-year-old nearly died after he was knifed six times, puncturing his lung, and was only saved by quick-thinking PCSOs who happened to be passing.

At Inner London Crown Court on Friday members of a teenage gang - including a 14-year-old - were sentenced for their part in the attack, during which an illegal pitbull was released inside the school.

However because it could not be proven who carried out the knife attack, no one has been convicted of the stabbing.

The school’s headteacher, who cannot be named for legal reasons, said: “I am disappointed that it was not possible to identify someone for what I regard as attempted murder . . . but we have to be happy that the pupil is now recovering and doing well.”

The gang’s lesser convictions - of violent disorder and fear and provocation of violence - means that all but one of them have already been released from prison due to time already spent in custody.

Detective Inspector Simon Rowe said the result was frustrating but convictions were secured.

“It is unfortunate we were unable to prove who carried out the stabbing but we could not prove any of those convicted made the attack,” he said.

“We will review the case if any new evidence comes to light.”

At the trial the court heard the gang entered the school on April 24 this year at 3.15pm, just as pupils were leaving for the day.

They let a pitbull off the leash, and one of the gang swung a metal chain at pupils.

The gang confronted and stabbed the victim, who innocently intervened to stop the dispute.

The victim was only saved by PCSOs, who were patrolling the area and stemmed the pupil’s blood.

A knife recovered at the scene could not be linked to those convicted and, while CCTV showed parts of the attack, the actual stabbing took place off camera, Wandsworth Police said.

Sentencing the gang, at Inner London Crown Court, Judge Diana Faber said the six convicted were part of a larger group of boys involved in the attack.

She said: “Boys, staff and police community support officers all became involved and the action took place in the school ground and school premises,” she said. “But none convicted were proven to be carrying a knife.”

Robert Anderson, 18, of Streatham - who had served four months in custody - received a six month supervision order and was ordered to serve 40 hours community service after pleading guilty to violent disorder.

The 14-year-old and a 16-year-old, who had both been in custody since April, pleaded guilty to the same charge and received supervision orders - three years and one year respectively.

Another boy, 16, pleaded guilty to the charge and was bound over - no supervision but the charge lays on file- for a year.

Shadrick Heslop, 18, of Stockwell, pleaded guilty to fear and provocation of violence, and was sentenced at another hearing to 18 months - which included time for other offences.

Another youth, 16, admitted the same charge and was given a conditional discharge.