A BRITISH woman accused of smothering her two young children to get revenge on their father was found guilty overnight of two counts of murder.

Fiona Donnison, 45, was facing a life sentence after jurors at Lewes Crown Court, in southern England, unanimously found her guilty of suffocating Harry, 3, and Elise, 2, while they were sleeping, on January 26 last year.

Donnison, who had been rejected by her partner Paul Donnison, the father of the two children, is believed to have carried out the murders at her home in Lightwater in Surrey, southeastern England, before stuffing the bodies into gym bags and driving them 145km to her estranged partner's home in Heathfield, Sussex.

The prosecution claimed that she had planned to kill Paul Donnison and frame him for the murders.

When her former partner failed to arrive home, a heavily sedated Fiona Donnison went to a nearby police station the day after the killings and confessed to murdering her two children. Officials found their bodies in the trunk of her Nissan Note car.

Donnison, who denied murder, had been suffering from depression at the time of the killings, according to her defense counsel, Simon Russell-Flint.

However, the prosecution said that the former credit manager was a narcissist with little empathy for others, including her children.

The trial heard that being made redundant from her job in the summer of 2009 had been a "massive blow to her ego".

Donnison, who was not married to Paul Donnison but had changed her surname by deedpoll, walked out on him with their children and her two teenage sons from a former marriage.

The pair reconciled but on January 14 Paul Donnison ended the relationship, leading Fiona Donnison to use the children as the "ultimate pawns" in an attempt to take revenge on her ex-partner.

Donnison, who sat with her head bowed as the evidence was heard, chose to stay in her cell as the jury returned its unanimous verdict.