The highest-ranking officer present when PC Keith Blakelock was killed during the Broadwater Farm riots described the estate as "impossible to police".

PC Blakelock, who was 40, died trying to protect firefighters tackling a blaze at the height of the unrest in Tottenham on October 6, 1985.

Jurors in the trial of Nicky Jacobs, 45, who is accused of murdering the policeman, heard the estate had been singled out by Scotland Yard because of its supposed association with drug dealing and taking and its potential for disorder.

Violence broke out there after a local woman, Cynthia Jarrett, died of a heart attack while police searched her house.

Chief Superintendent Colin Couch, who worked in the area's police station, told the court: "Tottenham was a working-class, multi-ethnic area and after the death of Cynthia Jarrett I was concerned that we would witness disorder."

But asked by Courtenay Griffiths QC, for the defence, if a contingency plan had been put in place for riots, Chief Supt Couch replied that there was not.

The court heard that the former Scotland Yard commissioner Sir Kenneth Newman had put together a list of "symbolic areas" police needed to keep an eye on at the time, which included Broadwater Farm.

Chief Supt Couch said the estate was not on the list because of crime, but because anyone could cross it from one side to another without descending to street level, making it "impossible to police".

He added: "We were policing it very sensibly."

The senior officer said that on the day of the riots he had met members of Mrs Jarrett's family and community leaders.

Tensions had gone from being "nose to nose, but not violent" during the afternoon, to a full onslaught at night.

Waiting outside after sending PC Blakelock's unit and firefighters into a building to deal with a blaze, he later saw two officers running out, and then a "silver lump" lying on the ground.

Then, he said: "Four or five jumped on him and appeared to stab him".

Asked about criticisms he received afterwards from rank-and-file police officers, Couch said: "They didn't have the decision to make. I did."

Jacobs denies murder. The trail continues.