- Video report by ITV News Correspondent Penny Marshall
The son of a woman jailed for life for killing his father with a hammer is hopeful her conviction for murder will be overturned when her case is reviewed by the Court of Appeal next week.
Sally Challen's landmark appeal on 27 and 28 February 2019 will be the first time the defence of coercive and controlling behaviour will be used in a murder trial.
Lawyers will argue that her conviction should be reduced to manslaughter as she was driven to kill her husband after years of psychological torment.
If successful, it could change the way the courts deal with domestic abuse.
Sally, who will turn 65 on the first day of the hearing, is hoping, along with her two sons David and James, that this is the last birthday she will spend behind bars after serving nearly eight years of a life sentence, reduced to 18 on appeal.
The Court of Appeal is set to hear how Richard Challen controlled his wife's finances, restricted her access to her friends and family and repeatedly called her 'crazy' when she confronted him about his affairs.
At one point he even cut the cables in her car to stop her from using it.
At the time of her conviction in 2011, ‘coercive control’ was not a crime in England and Wales and was only recognised in law as a form of domestic abuse in 2015.
The term and concept of coercive control was developed by the American academic and activist Evan Stark who will act as an expert witness at the appeal, according to The Times.
Sally's son David told ITV News that understanding the psychological abuse his mother was subjected to is not just about her case but is key to understanding domestic violence.
He told ITV News: "Coercive control is not a term that people have known about and when people learn about new terms, people are a bit dubious about it.
"But it's important to understand it because it's the root and foundation of domestic violence so you can't hope to battle domestic violence without first understanding coercive control."
Sally met her "charismatic" husband, when she was just 15.
She was left an "empty shell" after what David describes as 40 years of a constant "drip, drip, drip" of psychological abuse.
"Our dad was controlling. He controlled what we could all do really. Our mother was the main engine of the house and she would never answer back to him. He controlled everything that she did and where she would go," David told ITV News.
He said that while him and his brother knew their father's pattern of behaviour was wrong, the family did not understand how to describe it.
David said: "We all knew there was something wrong going on but we didn't have the language; there was no language there and we were all gagged victims. And now we've understood and we've been able to put it all together under a bracket of coercive control."
Richard's family and his oldest friend are also supportive of Sally's appeal, says David, who, along with his brother James and the campaign group Justice for Women, have helped bring Sally's case to the Court of Appeal.
David hopes his mother's appeal has a far reaching impact for those suffering at the hands of a psychological abuser.
"It's not just our appeal. It's an appeal for thousands of victims who are silenced by coercive control. Who are listening and watching this case to see if abuse will be heard and recognised property because in the courts the severity isn't recognised at all."
His mother, he says, had to serve a sentence for committing a crime, but it was crucial to recognise why she was led to kill their father.
"It's important to give her a chance at freedom because she's not been free since the age of 15. My dad captured our mother at the age of 15.
"And she set out into the world at the age of 56 and she didn't know how to cope because our father made her world revolve around him.
"And the dependency just crushed her and she didn't know how to exist."