A 17-YEAR-OLD was threatened with a knife the night his older brother Rob Knox was stabbed.

Jamie Knox was speaking at an Old Bailey trial today (Feb 10) where Karl Bishop, aged 21, of Beaver Lodge, Carlton Road, Sidcup, is accused of his brother's murder.

He told the court how he tried to help his brother tackle Bishop during a melee outside the Metro Bar, Sidcup, on May 24.

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The teenager said he had watched as his brother and several friends clashed with Bishop and a companion outside the bar earlier in the evening.

He later encountered Bishop a second time, and said he noticed the 21-year-old was carrying a knife.

Jamie claims Bishop said to him: "Do you want some?"

He said: "He seemed almost possessed. He had a smug expression on his face - a slight smile."

Jamie ran away from the scene and phoned his brother's friend Charley Grimley, saying someone had held a knife to him.

He was then driven to the Metro Bar and yelled to people out the car window to warn them.

When Bishop reached the bar, Jamie says 20 or 25 people surrounded him and his brother was shouting at him.

Jamie said their friend Andy Dormer made a move to take Bishop on and during the fight that followed a chair and bottles were thrown.

The teenager said he had to turn away from the scene, saying: "I couldn't believe what I was seeing."

When he turned back he saw his brother with his arms around Bishop and tried to intervene but was thrown on to the floor as others piled in.

Rob Knox was stabbed five times in the fight and lay down on the pavement next to Somerfield supermarket.

Jamie then phoned his mother to let her know what had happened.

During his testimony, Jamie Knox described his brother as "very protective" and someone he looked up to.

Mr Knox had finished appearing in Harry Potter and the Half-Blood Prince a few days before and his brother described him as in a "very upbeat mood, very cheerful."

Bishop claims he was acting in self-defence that evening.

Just a week before the group had also been involved in a fight with him over a mobile phone.

Bishop denies murder and five counts of wounding with intent to cause GBH.

The trial continues.