Police radio messages reporting that PC Keith Blakelock had “stopped breathing with a knife in the back of his head” were played to jurors at the Old Bailey yesterday.

The trial of Nicky Jacobs heard recordings of the communications by officers who attended the disturbances at the Broadwater Farm Riots, in Tottenham, on October 6, 1985.

Jacobs, 45, denies murdering the police constable as he retreated with colleagues and firefighters during the riots, when he was just 16.

The jury heard that PC Blakelock and other officers in his unit at first had the situation “contained” as they guarded firefighters trying to put out a blaze in a supermarket in the estate’s Tangmere block.

But after coming under attack by a mob of more than 100 rioters, some of whom were wielding knives and machetes, confused messages calling for “urgent assistance” could be heard.

One officer is heard in the recordings saying: “We have a PC who I think is dead, can we get an ambulance?”

When asked for an update on the policeman’s injuries, Chief Supt Colin Couch, the most senior officer on the scene, is heard replying: “Severe head injuries, stopped breathing.

“It is very serious, the PC situation here. Having tried to make him go back to breathing we now have a knife in the back of his head.”

When asked for more details, Mr Couch replied: “Standby, we’re doing resuscitation. I’m afraid to be rather vague but he’s thought to be 718 Blakelock from Muswell Hill, but regretfully as you can imagine the numbers are a little bit confused at the moment.

“I’m relying on other officers that knew him but we do have three officers from this unit that’s gone to hospital, one very seriously.”

Jacobs, most recently of Hackney but who lived in Manor Road, Tottenham, at the time, denies murder.

The trial will continue on Wednesday morning.