A 17-year-old on bail for robbery plunged a six-inch knife into a teenager who had his back turned, while children played around them.

Domingos Monteiro, of London Road, Ipswich, is today beginning three years in detention in a young offenders’ institution.

Monteiro, now 18, had pleaded guilty at Ipswich Crown Court to grievous bodily harm at Ipswich Crown Court.

The knife attack took place in Alderman Road recreation ground on November 8 last year.

Sentencing Monteiro, Recorder Craig Ferguson said: “This was a disgraceful attack in broad daylight in a public place while young children were playing.

“You used it (the knife) clinically - not in the heat of a struggle, and offensively.

“You had every opportunity to withdraw after the initial altercation and leave the park.

“As a young man on bail your instinct should have led you away from trouble.

“When (the victim) had turned his back in an attempt to escape your reach you plunged it into his shoulder.”

The court heard it caused a deep one-inch wound near the collarbone. The 18-year-old victim also sustained a second slightly longer wound to his upper left arm.

A pre-sentencing report praised by the judge showed Monteiro was at high risk of causing serious harm to the public.

It was also revealed that while in detention awaiting sentence he had been involved in a number of incidents, including one where violence had occurred.

Monteiro was part of a large group at the time, but did not use violence himself.

The wounding in Alderman Road occurred at around 4.30pm on November 8.

Monteiro had gone to the park where the victim was due to meet friends to play football.

An argument broke out and insults were exchanged. The pair were separated by others after they grabbed each others clothing and Monteiro had tried to slap the teenager’s face.

The prosecution claimed Monteiro walked away and returned 15 minutes later with the knife.

However, the court heard as part of Monteiro’s plea he said he did not leave the park and the knife was in a bag he had with him.

At the time of the incident Monteiro was on bail after appearing at Inner London Crown Court on a robbery charge.

After being given bail he came to Ipswich to live.

Monteiro was one of three people who mugged a woman for her i-phone outside Plaistow underground station on August 15.

He was sentenced to nine months detention for that offence to run concurrently with the three years he was given for grievous bodily harm.