A crowd of girls egged on their friend to stab a promising Croydon student, the Old Bailey heard today.

Giving evidence, Housing Association worker James Akintola said he heard girls shouting "stab her" before 17-year-old Sian Simpson was attacked in Mann Close on June 19 last year.

Chelsea Bennett, 19, formerly of Gilroy Court Hotel, London Road, has pleaded not guilty to murder, with the court told she was expected to claim self defence.

Witness Mr Akintola, who was holding a promotional event for the housing association in Mann Close that day, agreed with defence counsel Sasha Wass QC that victim Sian Simpson was "angry and aggressive" and the fight was not one-sided.

He told the court of seeing Miss Simpson with a knife first, but could not say if it was the same one later used by Bennett.

Another witness, Beverley Wright, who watched the events from her balcony window, told the court she saw Bennett approach Miss Simpson and they started arguing. Bennett then punched Simpson several times, she said.

She later saw the defendant trip and fall into a kerbside puddle, causing a few of the girls to laugh at her.

Moments later, she passed between her friends towards the victim, who shortly after fell to the floor bleeding.

The witness broke down in court as she recalled seeing the teenager falling to the floor after being struck in the chest.

Between sobs, Miss Wright said: "She slid down the front of the car then I just saw her roll back on the pavement and I saw blood on her top."

A friend of Sian's then ran over in distress and was heard shouting, "look what you've done, look what you've done", as the girls ran off, the jury heard.

The trial continues.