Judges play a key role in adopted children's lives. They approve care and adoption orders. They often choose between competing claims: birth parents- under the Article providing a Right to Family Life v. local authority plans for foster or adoptive parents using the Children's Act, in which decisions should be made 'in the best interests of the child.' This is truly the work of Solomon.

Because of tight family law reporting restrictions, few outside the system know what goes on. Nor do they know the human cost of delays that are mounting as more children are taken into care - but with no more professionals to deal with them. No wonder last year saw the lowest number of adoptions on record.

The PM rightly wants to bring the waiting down to twelve months. But that means difficult choices: just put fewer children taken into care? That leaves them at risk for longer. More and better trained social workers, and Children and Family Court Advisory and Support Service (Cafcass) officers to act as guardians and do assessments? But they all need more time to help children and families and less time complying with complex procedures. More Family Court judges? Perhaps more Family Group Conferences to resolve care matters could diminish the load of elaborate court procedures.

Meanwhile, the children languish in limbo.

Worse still, some children are returned by prospective adopters. Some, like Coner in our film, was returned after two turbulent weeks at the age of one and a half. Others were returned after nearly three years of an adoption placement. That means they have lost two families already. Astonishingly, we learned almost no records are kept of adoption breakdowns or of their causes. Adopted children come off the case load, and if returned, appear 'at the front door' - sometimes literally - as a fresh case of children at in need. If would-be adopters don't wish to explain, there is no way to make them, and no form to be filled out. So no solid research or statistics exist about the most important element in this high risk transaction. In six months in Coventry alone, we observed or heard about seven returned children. The official figure was only one.

One issue may be support, or lack of it. Foster parents get emotional, physical and financial support until children in their care reach 18. With adopters all three are usually removed soon after adoption. Sadly, once children are placed with a family, potential adopters can change their minds at any point. Along with the lack of professionals - perhaps compounded by it - this is the elephant in the room.

The film we’ve made about adoption in Britain is now showing (for those within the UK who can get to the BBC website OK). We had the rare accolade in this field of having a High Court Judge endorse a film about adoption breakdowns and delays. Last Friday Mr. Justice Moor had to decide about one of our cases. He said that in his view there was no doubt the broadcast was very much in the public interest, and of all children who are in care.

Films are often made on a shoestring. This one was made on a tightrope. In many years of making access films in normally closed situations, this was the hardest. Our starting point was a BBC commission to make a third film for Panorama  about vulnerable children.

Navigating access for each case meant traversing a barrage of legal barriers, hazards and concerns. Consent involved negotiating with everyone involved who shared parental responsibility: foster families, the local authority legal and social workers - and birth parents who may have had no connection to their children for years. We had to try for consent of all parties - including prospective adopters - in every case.

Even after previously successful films, we met anxiety about the media. Each meeting, with each social worker, involved the intrepid filmmaker Clare Johns in new negotiations. Some anxiety was rightly on behalf of the children. Often it was fear of being criticized in public.

But the power of film to engage a large audience with serious and difficult social issues justifies the effort and the effort to publicise these often intensely private subjects. We have a problem with adoption in the UK - and with “Cinderella services” in general - all those tough areas of social policy that most people prefer not to think about much. This kind of media has a responsibility to keep Cinderella in our minds.