A former police officer who killed a woman during a 100mph "joyride" has been jailed for six and a half years.

Malcolm Searles, 24, had left his police station to deliver an 18th birthday card to his sister when his car hit Sandra Simpson, 61, on 23 August last year.

Southwark crown court, in London, heard that Searles was in a marked patrol car with blue lights flashing and sirens sounding as he repeatedly broke the speed limit. An on-board computer recorded the vehicle travelling at 104mph in a 40mph zone during a "prolonged course of dangerous driving lasting over an hour".

Searles sped through "densely populated" housing estates where children were playing football on the pavements and double-sided parking limited the streets to single-file traffic, the court was told.

Sandra Simpson. Photograph: IPCC/PA

He was travelling at 56mph in a 30mph zone in Bromley, Kent, when he hit Simpson, who died of head and chest injuries.

Michael Mulkerris, prosecuting, told the court that had Searles been driving at the legal limit he "would have been able to stop" in time to avoid his victim.

The judge, Geoffrey Rivlin QC, said his driving had been "described as no more than a dangerous and indeed, if I may say so, a hair-raising joyride".

"You used, or rather abused your privileged position of driving a police car with its emergency signals operating for no other reason other than to provide a cover for racing along the streets," Rivlin said.

"Mrs Simpson's daughter in her impact statement said she finds it unbearably difficult to live with the fact you were not answering an emergency. She said, and I quote: 'It was like he was driving dangerously deliberately because he knew he could get away with it.' I believe she has articulated what you were doing perfectly."

The judge said Searles had indulged in a "prolonged, persistent and deliberate course of very bad driving. You must have known for considerable stretches that at times you were placing members of the public, including the occupants of your own car, at serious risk of either being killed or injured."

Rivlin said another aggravating feature of the case had been Searles' attempts to justify his driving by claiming he had been following a speeding car he believed had been stolen.

Searles, from Swanley, Kent, pleaded guilty at an earlier hearing to one count of causing death by dangerous driving, one count of dangerous driving, and two counts of speeding.

Outside court, Simpson's son-in-law, Luke Brooks, said the family's "world fell apart" when they were told details of the accident.

"As a family we are angry that Sandy was robbed of her golden years," Brooks said. "She was in the prime of her life, a fit, healthy and young 61. Whatever the sentence passed here today, we do not feel it would be adequate in comparison to our loss. We hope that today's conviction and sentencing will cause other police officers to question their behaviour while driving and the potential consequence for them and the general public."