London Evening Standard/London

A four-year-old boy yesterday became the youngest witness to give evidence in a murder trial at the Old Bailey.

A girl of six was also due to be questioned in the trial involving allegations that a mother was burned to death with petrol by her jealous boyfriend.

The two children allegedly saw Julie Beattie, 24, staggering in the street with her clothes and flesh on fire in Walworth in July last year. Her partner Ashley Williams had also battered her over the head with a hammer in fury at her affair, the court has been told.

Williams, 48, of Walworth, has pleaded not guilty to murder.

The children are the youngest witnesses at the Old Bailey since a jury in a Baby P-related case saw a video of a three-year-old girl giving evidence.

She answered questions from a barrister in court when aged four.

The jury was shown a video of the boy answering questions from police officers after Beattie’s death. He was then asked questions by Williams’ lawyers via a videolink from a separate room in the Old Bailey. The same procedure was due to be followed with the six-year-old girl.

The court has heard that Beattie suffered 90% burns but whispered to a neighbour, “Ashley did this to me”.

She died in the Chelsea and Westminster hospital. On the day that she died, she had begun to move her belongings out of the family home.

When Williams — who has eight children from a previous marriage as well as four with Beattie — found out he came home from work to stop her. Her new lover was Williams’s son from a previous relationship — also called Ashley, said Edward Brown QC, prosecuting.

“Julie Beattie died a terrible death. She survived until the evening,” said Brown. “She was conscious and coherent for a time. She said, ‘Ashley did this to me’.”  Beattie had told her sister Lucy she was leaving Williams and when he arrived home Lucy left. When she returned she heard shouting.

Brown said: “Through the partially opened door, Julie Beattie was heard to call out, ‘He’s got a hammer... he’s going to kill us all’. Julie was still in the kitchen but staggered out on to the drive and road. She was seen to be still on fire.”

The court heard that the relationship between Williams and Beattie had been deteriorating and got worse when Ashley Jnr came to live with them in September 2012 and started a relationship with her five months later. The case continues.