Two teenagers who killed an elderly woman by stuffing a lit firework through her letterbox have been locked up.

Josephine Smith, 88, is believed to have been asleep in bed when the Megaburst firework exploded and set her home ablaze on October 28 2021.

A 17-year-old boy, who delivered the firework for a dare, had pleaded guilty to affray, manslaughter and arson and was locked up for three years and eight months.

Kai Cooper, 19, of Leatherhead, Surrey, who encouraged him, was found guilty of her manslaughter and arson, having earlier admitted affray.

He was locked up for six-and-a-half years with a further two years on extended licence.

Judge Mark Dennis said the two defendants had “mischief in mind” when they set out to buy fireworks that evening.

He told them: “Your wanton and reckless conduct led to the death of a vulnerable and much-loved person.”

As they appeared at the Old Bailey to be sentenced on Friday, the court heard the pair had been in trouble since the age of 14.

The younger boy, who has autism spectrum disorder, had convictions for battery and public order offences and had set light to things in the past.

Cooper had convictions for common assault, street robbery and battery that the judge said “showed a violent aggressive streak to his character”.

Just 24 hours before the fatal arson, the pair were involved in an attack on a woman in Ilford town centre which was captured on Cooper’s mobile phone.

The video clips showed a young woman walking towards the camera and the 17-year-old holding a pole.

As the youth struck her, the women held her arms up to shield her face and Cooper shouted out: “Smoke her, smoke her bro.”

A second video clip showed the woman on the ground and the youth standing over her, attacking her with his foot.

Cooper is heard to say: “Boot her in the face, man. Just one tap on her face. Do it. One boot in her face. Stamp it.”

The youth then stamped on her face and Cooper responded: “Yes bro.”

The next day, the pair went into a firework shop in Romford, east London, and Cooper asked for something that would “go far and quick”.

Cooper commented: “I’m trying to get fireworks, let them off at people. People are going to get terrorised tonight.”

The pair then made their way towards Mrs Smith’s home in Queens Park Road which was randomly selected.

En route, the two youths set off fireworks in the street, next to a restaurant and a pub, near cars, and even towards frightened pedestrians.

Acting on a dare, the 17-year-old lit a firework and put it through the letterbox of Mrs Smith’s home.

There were two explosions and a fire ripped through the house.

By the time firefighters had arrived, the property was smoke-logged and Mrs Smith had died in an upstairs bedroom.

Ms Smith’s son, Alan Smith, who attended court, said: “Losing Mum in such a horrible way has haunted our entire family. Mum was so loved by all of us and had many more happy years ahead of her.

“The issue surrounding the sale of fireworks to the public is a fight that we intend to continue. In addition, the irresponsible way those fireworks were sold on that night haunts all of us that have seen the footage.”

Previously, the younger defendant was handed a youth rehabilitation and training order and Cooper given six weeks in a young offenders institute for the earlier filmed attack on a young woman.