A young mother has been accused of putting her boyfriend first after he allegedly crushed her toddler to death with his car seat because he was annoyed.
Adrian Hoare, 23, is accused of failing to prevent Stephen Waterson from pushing the chair twice into Alfie Lamb as he sat in the footwell.
As he did so, he allegedly said: "I will not be told what to do by a three-year-old."
Alfie was found unresponsive by paramedics in February 2018 and went into cardiac arrest. He died in hospital three days later from crush asphyxia, the Old Bailey heard.
After the incident, Hoare did not blame Waterson straight away because she said her relationship with the 25-year-old was "just too important", Duncan Atkinson QC claimed.
Alfie collapsed in Waterson's convertible Audi on the way home to Croydon from a shopping trip in Sutton, south London.
As well as Hoare and Waterson, there were two other adults in the car and Alfie and another child were forced to sit in the footwell.
Jurors on Friday were shown CCTV of Alfie, who was 3ft tall, appearing to run to keep up with the group as they left Halfords car park and later returned with their shopping.
Mr Atkinson asked Hoare: "Whose pace are you walking at? What allowances were you making for Alfie's little legs? Why is Alfie having to run?"
The defendant replied: "It's just the way I walk even if it's just me and Alfie. Alfie always runs."
Mr Atkinson added: "Until he got into that car on the way back from Sutton, he was fine wasn't he?
"And by the time that the car reached Adams Way he was very far from fine, wasn't he? Something had to have happened in that journey?
"So when doctors and police start saying something happened to Alfie, you knew it had to have happened in the car. Were you not thinking it must have been Stephen?"
Hoare replied: "Not straight away."
The prosecutor said Waterson had moved his seat back deliberately and asked if he was annoyed the second time he moved his chair back.
She agreed and added: "To begin with I did not blame anyone for what happened."
Mr Atkinson said: "Was it your relationship with Stephen was just too important?
"Wasn't the reality you just put what Stephen wanted first?"
The defendant denied it.
Earlier, Waterson's lawyer suggested his chair had nothing to do with Alfie's injuries and Hoare must have "done something".
Tana Adkin QC asked Hoare if she was trying to "cover up something you did in the back of the car", which she denied.
Hoare told the court Alfie had previously travelled in the car's footwell.
Ms Atkinson asked Hoare if she slapped Alfie because he said he did not have enough room, to which she said no.
The lawyer said Alfie was crying, screaming, coughing, and calling for his mum when the seat was moved back a second time but Hoare did not pick him up.
Hoare said she would have moved Alfie if she thought he could not breathe, and in hindsight feels like she let Alfie down.
Ms Atkinson added: "You could have kept your son out of that footwell, couldn't you?"
The defendant said: "Yes, but Stephen said we was all going together."
Mr Atkinson observed: "It's all about Stephen."
Hoare, originally from Gravesend, Kent, denies manslaughter, child cruelty and common assault on fellow passenger Emilie Williams.
Waterson denies manslaughter and intimidation of the driver Marcus Lamb.
The couple and Williams have pleaded guilty to conspiring to pervert the course of justice by making false statements to police.