Last Night's TV: Madeleine, One Year On: Campaign for Change ITV1

You can't always blame the parents

Journalists and commissioning editors like round-figure anniversaries, which is why, nearly one year on from Madeleine McCann's abduction, ITV1 cleared two hours of its prime-time schedule for a programme about the worst 12 months in her parents' life. And one of the more piercing elements in Madeleine, One Year On: Campaign for Change was the reminder that for Kate McCann there are no moments that aren't commemorative.

"Every minute, every hour, is time without Madeleine," she said, recalling the day after she'd discovered her daughter had been taken. "That Friday, I was watching the clock in the police station... so, that's so many hours, that's so many hours, and then it's 24 hours, and you're back to another dark, cold night." And she's been assailed by other anniversaries since, too, marking off the calendar with straws to clutch at. "I remember in the early days, someone saying a little boy had been taken, he was returned at 17 days, and, you know, it seemed like a lifetime... but then we went past that, and then I can remember Sabine Dardenne, I think she was 80 days, and we went past that... but I think the one that's kind of kept me going really was Elizabeth Smart... it was 278 days for her, and it's 278 days for us tomorrow..." At which point, the number caught in her throat and she couldn't carry on. Counting how many days have passed isn't just a matter of editorial scheduling for her: it's a life sentence.

The McCanns met up with Elizabeth Smart's father in Washington DC, while pursuing the cause that has allowed them to shape their pain into something potentially constructive: a campaign to get the European Union to adopt an equivalent to the US's Amber Alert system, which allows for the rapid dissemination of information about abducted children. It was clearly the opportunity to push for that change, as well as jolt their daughter back into the minds of the general public, which had motivated them to take part in this film, trading some of their private life and their private emotions for a commodity – publicity – that they still believe might be life-saving. So anyone who wanted a forensic, minute-by-minute account of what happened on the evening of 3 May last year, or a detailed account of the rumours and half-truths that swirled around the couple in the weeks and months that followed, would have been disappointed. This wasn't for conspiracists or McCann obsessives. But anyone interested in what it felt like to be the focus of the year's most hysterical news coverage couldn't have failed to be moved and appalled in equal measure.

They still get a lot of letters, the McCanns, sorting them out into boxes marked "well-wishers", "ideas", "psychics" and "nutty". Incredibly, they also need a box marked "nasty" for messages such as the one that Gerry read out at the beginning of the film. "How can you use money given by poor people in good faith to pay your mortgage on your mansion? You fucking thieving bastards. Your brat is dead because of your drunken arrogance. Shame on you. I curse you and your family to suffer forever. Cursed Christmas. If you had any shame, you would accept full responsibility for your daughter's disappearance and give all the money back. You are scum." This heart-warming expression of support had been written inside a Christmas card. The Daily Express, by contrast, chose to print its hate mail on its own front page, confident that there were enough readers out there who would prefer infanticide to unresolved mystery – or to no McCann story at all. And all the time, the McCanns themselves live a life horribly suspended between what might have been and what could happen next, between "if only" and "maybe".

It's a "quasi-real" existence, Gerry McCann explained, haunted by the child who isn't there. "With three kids, there's always lots of washing," Kate McCann said, explaining that routine chores sometimes offered a distraction, and forgetting, even as she spoke, that she now has less washing to do. And the suspended uncertainty must be far worse than grief, since it has every agony grief can command without its promise of eventual parole. "There are a host of scenarios under which your child could be alive," the head of America's National Center for Missing & Exploited Children said, trying to reassure them. But virtually none that a parent could bear to dwell on without screaming, you thought. The McCanns remain practised at the rhetoric of confidence – the brave insistence that one day she will return – but even they can't keep it up perpetually. "We need to know," said Kate. "The thought of living like this for another 40 years isn't exactly a happy prospect." One hopes that the sender of that vitriolic Christmas card was watching last night, to understand that his or her curse was completely redundant and to feel a little shame at having uttered it.