During police interviews McIlwaine stated that she had considered taking her own life.

She described taking a knife from the kitchen, returning to the bedroom and moving the child before repeatedly stabbing her sleeping partner.

Prosecutors argued that she made rational choices which demonstrated being in control of her actions.

In October 2024, a jury rejected McIlwaine's case and unanimously found her guilty of murder.

Defence lawyers argued on appeal that they had been misdirected and reached a verdict which went against the weight of expert evidence.

Central to the appeal was how the trial judge advised jurors on the legal test for the loss-of-control defence.

Instead of asking them to decide if someone of similar characteristics to McIlwaine "might" have reacted similarly, the question posed was "would" that person have acted in the same way.

Dame Siobhan, sitting with Lord Justice Colton, backed defence submissions that the wording used wrongly imposed a higher threshold for establishing probability.

Two consultant forensic psychiatrists had also concluded that a properly directed jury could find McIlwaine met the criteria necessary to establish loss of self-control.

Both witnesses highlighted the psychological impact of prolonged abuse and the recognised behaviour responses of victims in coercively controlling relationships.

"The misdirection we have identified was highly material, given the uncontradicted expert evidence," said the Lady Chief Justice.

"The appeal succeeds… and the conviction for murder will accordingly be quashed."

Adjourning the case until 16 October, she told prosecution counsel: "You have to come back to court on what steps you want to take."