Eyewitness 'John Brown', a former member of the Park Lane Boys gang, who accepted a caution for assaulting his partner in 2010, said defendant Nicky Jacobs used a machete with a 12-inch blade during the attack on Pc Keith Blakelock.
He told the jury that he himself had kicked the officer some 10 times after he went to the ground.
Asked why, he said: "Looking back on it I don't know...It was the excitement of the situation, I just rushed forward and kicked him about ten times."
The witness said he had been paid a £5,000 reward by the police after giving a statement during a renewed police investigation into the killing in 1993.
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Expect some sunny spells with odd spots of rain for Sunday morning with scattered, heavy and possibly thundery showers in the afternoon.
Detectives have released a CCTV image as they hunt for man who sexually assaulted woman at bus stop in east London.
Shops and restaurants on the route of the Notting Hill Carnival have boarded up as shop-keepers and residents aim to protect their property.