A young mother claimed her toddler had gone to sleep after his head was fatally wedged between a rear seat and front passenger seat, jurors heard.

Passenger Emilie Williams, 19, had asked Adrian Hoare, from Gravesend, why her three-year-old Alfie Lamb had gone "quiet" when Stephen Waterson is alleged to have crushed him.

Miss Williams added "controlling" Waterson would not let Hoare sit Alfie on her lap and "had made" the toddler sit in the footwell.

Alfie died from "crush asphyxia" in hospital three days after he passed out in the Audi A4 on the way back to Croydon, the Old Bailey heard.

Waterson, 25, and Hoare, 23, are accused of manslaughter after he allegedly twice moved his car seat back when Alfie was behind him in the footwell.

Miss Williams, who was sat in the rear next to Adrian on February 1, said she knew Waterson for about nine years.

Yesterday she said he was cheating on former Northfleet School for Girls pupil Hoare when Alfie died and threatened to kill Miss Williams if she did not lie to paramedics and police that the toddler fell ill in a taxi.

Her police interviews heard by the jury Miss Williams described what happened in the Audi A4 and said: "'He was moaning that I didn't have enough room and his legs were squashed.

"'I think it was 'mummy my legs are squashed and I cannot move.' I'm pretty sure.'"

After Waterson was said to have moved his seat forwards, she said: "He was just lying with his head back on Adrian's leg because he said he was tired.

"Alfie wasn't crying when the seat was pushed forward and he looked fine."

She said he coughed for a "couple of seconds" before she asked Hoare, who has also lived in Chatham, why he had gone quiet.

Ms Williams told jurors: "I asked Adrian if he was okay because he went quiet and she checked him and said he had gone asleep."

Answering questions from Katy Thorne QC, representing Hoare, she described how Waterson was "controlling" and could "scare her".

Miss Williams said he never would let anyone stay in his Croydon flat on their own, held the only copy of the keys and locked his guests inside with him.

Miss Williams added Waterson took Hoare's mobile phones, controlled her Facebook page, wanted to know what bank accounts she owned and followed to cash machines.

Asked what Waterson told her he would do if she ever told the truth about Alfie she replied: "He said that he would kill me."

She added he repeated the threats "lots of times" and when asked: "While Stephen was in a relationship with Adrian did you know he was cheating on her?" she said "yes."

Ms Thorne QC asked: "Did you think at the time that it would be dangerous not to have car seats?

Moss Williams added: "Yeah. I asked Stephen if we could put at least one car seat in the car and he said 'no because he would not be able to hide when he went and met people.'

"There would have been (enough room) if one person sat in the middle."

The trial continues.