Anne Diamond: 'There in the cot, a little, stiff, cold statue of a child where my cuddly, warm, milky baby had fallen asleep'

Viewpoint from the broadcaster and campaigner who lost her baby to cot death

We've known for some time that the link between cot death and smoking was even stronger than the link between lung cancer and smoking, yet many in the medical world chose to ignore it, because it couldn't be scientifically proved.

In 1991, we were losing 2,500 babies to cot death in the UK. The terrible morning of 12 July was when it happened to my family. It was my eldest son's birthday, and after I'd woken him with a birthday song, I went on to my baby's nursery. What I saw I describe as every mother's nightmare. There in the cot, a little, stiff, cold statue of a child where my cuddly, warm, milky baby had fallen asleep.

I was treated with sympathy, but also astounding complacency. I was told that I should "cheer up and have another one". In New Zealand, however, they couldn't afford such complacency. They had the highest cot death rate in the world – and couldn't tell why. So they launched a three-year epidemiological study. Every time a baby died, they researched everything from age, environment, dummies, parental smoking, breast milk or formula – everything. They also took data from at least two "controls" ( babies who had not died that night) to draw comparisons.

After 18 months, the results were so dramatic that they felt compelled to turn the study into a campaign. Because the babies who were dying were the ones on their tummies and those whose parents smoked. New Zealand's most famous female broadcaster went on TV every night asking parents to turn their babies on to their backs, and to stop smoking near them. The cot death rate plummeted almost overnight.

Back home, our Back to Sleep campaign proved that the advice worked. In 1991, I presented a TV advert with the four life-saving tips: sleep your baby on his back; don't smoke anywhere near him; don't overheat him and go to the doctor if he has coughs, colds and sniffles. Our cot death rate fell dramatically, from 2,500 down to around 300 a year.

We had to admit we don't know why the advice worked. But the scientists have always wanted proof. Now the tough question is: will this proof save more lives? Will the single mum living in a miserable tower block, who clings to her pack of ciggies as the only thing that keeps her sane, be able to kick the habit? I think not. And that's what's stopping us from saving those 300 precious lives a year.