Several years ago, I met an extraordinary woman named Sharon de Souza. In 2008, Sharon witnessed the murder of her 24-year-old daughter, Cassie. Cassie was stabbed to death by her estranged husband in front of their two young sons as she attempted to flee to the safety of a women’s shelter.

With the help of Refuge, a charity that supports women and children experiencing domestic violence, Sharon secured an inquest that would shed light on the circumstances surrounding Cassie’s death. It was a long battle, but in February this year the inquest finally took place.

After hearing from a number of police officers and other professionals who had been in contact with Cassie in the months and weeks leading up to that day in July 2008, a jury concluded that two separate police forces and the Crown Prosecution Service (CPS) all failed to take appropriate steps to safeguard Cassie’s life. They also found that, had the CPS and Sussex Police taken these steps, there is a substantial chance that her life could have been saved.

The sad truth is that Cassie’s story is not unusual. Domestic violence takes an enormous death toll. Every week two women are killed by current or former partners in England and Wales. And so, up and down the country, there are thousands of bereaved families struggling to come to terms with the loss of a beloved mother, daughter or sister. In too many of these cases, the police – and other state agencies – have failed to protect women and children at their moment of greatest need.

My own mother experienced violence at the hands of my father. I remember the police being called to our house on many occasions. As a child, I heard police officers standing in our small living room saying things like, “She must have provoked him,” or, “Well, Mrs Stewart, it takes two to make a fight.”

They had no idea. As a child I didn’t have the words to explain, but as an adult I can tell the truth.

The police had a duty to protect me and my mother, and they failed in that duty. They left us powerless and vulnerable. It shocks me that, decades later, women and children are still being let down by those agencies and by professionals who have a legal duty to protect them.

Of course, much has changed since my childhood. Many police officers do take domestic violence seriously. Yet the negative attitudes that I encountered as a small boy are still embedded in our culture and in our institutions. I have heard alarming comments from women using Refuge’s services about the poor response they still receive from police officers.

One woman was told that she should “just make up” with her ex-boyfriend though he’d assaulted her – an incident that the police officer involved referred to as “just a domestic”. Another woman reported that her partner was let off with a caution after he held a knife against her throat. These comments show how little we have progressed as a society in taking a stand against domestic violence.

It takes extraordinary courage for a frightened, abused woman to report her abuser to the police. When women make that brave step, it is vital that they be believed, supported and protected. They must have the full force of the law behind them.

Cassie’s story also proves that it is not just the police who fail victims of domestic violence. The inquest into her death found that the CPS was responsible for a number of failings. In 2012, Refuge gave expert evidence at the inquest into the death of another woman, Sabina Akhtar, which found Greater Manchester Police, Manchester social services and the CPS accountable for serious and significant failings that possibly contributed to Sabina’s death.

Our system is broken. Women and children continue to die in large numbers because they are not given the support and protection they deserve. Refuge is calling on the Home Secretary to open a public inquiry into the response by the police and other state agencies to victims of domestic violence. In my mother’s name – and in the name of women like Cassie – I support this call. We need a bold shift in the way we, as a society, view domestic violence – and in the way our public services and state institutions respond to victims. Those negative attitudes I encountered as a small boy – attitudes that allowed the violence to continue – must be banished once and for all.

Patrick Stewart is a patron of Refuge. For more information and to sign Refuge’s petition calling for a public inquiry, visit: refuge.org.uk/publicinquiry