The mother of a three-year-old boy allegedly crushed by a car seat has been found guilty of child cruelty.
Adrian Hoare, 23 allegedly failed to prevent her boyfriend Stephen Waterson, 25, from squashing Alfie Lamb in the footwell of his Audi convertible with his seat in February last year.
Afterwards, Hoare and Waterson, the adopted son of former Tory minister Nigel Waterson, lied to police about what happened.
Following an Old Bailey trial, a jury was unable to decide whether Waterson was guilty of Alfie's manslaughter, but found him guilty of intimidation of a witness in the case.
Hoare was cleared of manslaughter, but found guilty of an alternative charge of child cruelty and common assault on another witness.
The defendants had previously pleaded guilty to conspiracy to pervert the course of justice.
On February 1 last year, the defendants had gone shopping for cushions in Sutton, accompanied by Alfie, Emilie Williams, 19, Marcus Lamb, 22, and another young child.
Jurors were shown CCTV of Alfie running to keep up with his mother moments before he was put in the car for the journey back to Croydon, south London.
It was alleged nightclub worker Waterson became annoyed at Alfie's crying and twice moved his front passenger seat into him as he sat at his mother's feet.
Jurors heard the maximum space in the foot well was 30cm, and, at the touch of a button, that could be reduced to just 9.5cm.
Waterson, who is 5ft 7in tall, initially pushed his front seat back to give himself more leg room, according to Ms Williams, who is the sister of his ex-girlfriend.
Alfie screamed for his "mummy" but Hoare just slapped him and told him to "shut up", said unqualified driver Mr Lamb, who was Alfie's cousin. By the time they arrived at Waterson's home in Croydon, south London, the boy had collapsed and stopped breathing.
As medics desperately tried to revive him, Waterson fled the scene and Hoare spun a web of lies, claiming she had been in a taxi.
Alfie, nicknamed "Little Tarzan" by the defendants, died from crush asphyxia three days later.
Meanwhile, Waterson gave officers a false name and false statement and sold the Audi.
He allegedly threatened to make Hoare and the other witnesses "disappear" if they did not stick with their fake stories.
Hoare eventually broke her silence and told her half sister Ashleigh Jeffrey in a taped conversation handed to police.
But Waterson blamed Mr Lamb, who he regarded as a step brother, for being a "grass" and put his foot on his head during a violent assault in Crystal Palace Park which was filmed on his mobile phone.
Jurors were told Waterson was a controlling womaniser who used his family connections to "powerful people" to control and manipulate people.
He also had a violent temper with three previous convictions for attacking an ex-girlfriend and his sister's husband.
Giving evidence, he denied he would hurt a child and said he moved his seat back once by up to an inch.
It was suggested on his behalf that Hoare must have done something to cause Alfie's injuries.
Prosecutor Duncan Atkinson QC told jurors both played a part in Alfie's death, saying Hoare "fundamentally and fatally" failing to act.
Mr Atkinson said: "When he started to cry, when he said he did not have enough room, when he coughed as if he was about to be sick, when he was screaming, when she could see he did not have enough room.
"All she needed to do was pick him up and she didn't and he is dead."
Responding to the verdict, Scotland Yard's Detective Chief Inspector Simon Harding said: "He was a vulnerable three-and-a-half-year-old who had his life in front of him. He had no-one to care for him on that day."