Neglect Copyrighted image Credit: Production team Someone To Watch Over Me producer Sarah Johnson explains how she came to make the series, and her memories of the filming.

It all started about four years ago. I was coming to the end of making a BBC ONE series about the adoption process, called Love Is Not Enough, when I rang one of the social workers I'd been filming. I was told that she was off sick because a client had tried to run her over. I couldn't quite take it in and was naturally horrified. Most of the social workers I'd filmed with for Love Is Not Enough worked with adopters and foster carers, but this social worker was different because her responsibility was for the children. I immediately realised that the adoption series was the second half of a much bigger story.

A couple of years and a commission later, myself and two producer/directors started filming with some of Bristol's 190 child care social workers. It's a strange job title, child care social worker, and it took us a while to work out what it meant and what they do. I'm sure they'd give a more precise explanation, but basically what child care social workers do is care for and protect vulnerable children. No one should feel too bad for not knowing much about them because child care social work is an all but invisible emergency service – except, that is, until things go wrong.

Over the year or so we filmed with Bristol's social workers I kept reminding my team that our aim was to get inside the social workers' heads. What does it feel like to make potentially life or death decisions about children? How do you weigh up the rights of the parents against those of the child? What's it like to have your profession so little valued that you lie about what you do for a living? How does it feel to have rescued a child from a life of intolerable abuse but have, at the same time, taken them away from the parents they love?

At the beginning of our filming a social worker told me that they'd never worked with parents who didn't love their children. No matter how abusive or neglectful, they all loved their children. At the time, I found that statement difficult to believe. But, a year later, I believe it. And that, I suspect, is what makes child care social work so difficult, frustrating, involving and, sometimes, unbelievably rewarding.

From all the pain and anguish we witnessed, the moment that sticks most vividly in my mind is the smallest of smiles. Jo, one of the social workers we filmed, had decided to support a mother who was pregnant again, having previously had three children removed. The baby was born, went home, but after a few months became sick with a high fever. On the day Jo was due to hand the case over to a long-term social worker, the parents brought the baby into hospital. "You've done the right thing," Jo gently told the mother. In those few words Jo let the mother know that not only had she done the right thing by bringing her baby into hospital, but that she had repaid Jo's belief in her that she could be a good mum to this baby. After a few moments of reflection on all she'd achieved, the mother allowed herself the tiniest smile of satisfaction.

Someone To Watch Over Me in more depth: