For over a decade, Her Majesty The Queen has been working to raise awareness of domestic and sexual violence, and it’s become an issue close to her heart. In this ITV1 documentary, Queen Camilla opens up about her work – and the tearful moment that drove her to fight for the cause.

“It’s such a heinous crime,” she says early in the documentary. “If we could just get people discussing it and talking about it, people are so shocked by what they hear that – rather like me – they want to say, ‘Hang on a minute, maybe there’s something we can help with to put an end to it.’”

The special follows Queen Camilla, 77, as she attends official engagements and private meetings with survivors and campaigners, striving to remove the stigma from the issue. However, she reveals that it was going to an event organised by SafeLives – a domestic abuse charity – that ignited her passion for the cause.

There she met the mother of a mum-of-two who was murdered by her partner, and listened to a speech by the victim’s best friend. “My reaction I’m afraid was to cry,” Her Majesty admits. “I looked around and there were quite a lot of police and quite a lot of quite hard-nosed journalists around and there wasn’t a dry eye in the place. We were all so shocked by what we heard. It was certainly my reaction. I thought, ‘I just want to do something about this.’”

The mother Camilla met was Diana Parkes, whose daughter Joanna Simpson was beaten to death by her estranged husband in 2010. Last month, Diana and Joanna’s best friend Hetti Barkworth-Nanton accepted Pride of Britain’s Special Recognition Award for their work with the Joanna Simpson Foundation.

Both credit Queen Camilla’s unwavering support from that initial meeting onwards as invaluable in their mission. “She always says to me, ‘You are the one who made me want to get involved in this issue,’” Diana says of Her Majesty. “She is the most compassionate lady, she understands totally how I am feeling.”

Last year there were an estimated 2.1 million incidents of domestic abuse in England and Wales. Over the years of her campaigning, Queen Camilla has met with many survivors and campaigners to understand the different forms abuse can take – particularly coercive control, which only became a criminal offence in 2015 after a campaign by the then Home Secretary Theresa May.

“You meet somebody, you think they’re wonderful and attractive and love you… and then bit by bit, they start to undermine you,” Queen Camilla says. “They take away your friends, they take away your family… and then when you start questioning it these people become very violent.”

By spurring on organisations that support victims of domestic violence and abuse, The Queen hopes they’ll show victims that there is an escape. “You can imagine how terrifying it is for a woman to be stuck with a very violent partner and feeling that fear every single day,” she says. “And they think to themselves, ‘Maybe there is a way out.’”

In one scene, Queen Camilla visits a women’s refuge, where resident Natalie – whose identity is hidden – tells of the harrowing abuse she faced at the hands of her partner for the first time. “The odd slap turned into a punch and then beating,” she says. “The [violence] went on sometimes for days. I was embarrassed and ashamed so I just kept it to myself. I couldn’t get out, I was a prisoner.”

After the police were called by Natalie’s friend, an officer put her in touch with a support worker – who placed her in a women’s refuge. “I think through getting some of the wonderfully brave survivors to actually get up and talk about it has made people sit up and listen,” Queen Camilla says. “There are a lot of feisty women who have been through it, come out the other side and are now telling people how to do it – and that is what we want.”

Watch Her Majesty The Queen: Behind Closed Doors, Monday 11 November, 9pm, ITV1 and ITVX