The question is whether measuring these parameters shows whether this intervention has been effective, and no, it won't, because there are a lot of other things that happen besides the change in advertising. For example, with respect to diabetes, you're going to have changes perhaps in behaviour in terms of kids becoming more active or less active. That's also going to be affecting the rates of diabetes. A change in the rate of diabetes is not going to solely reflect this change. Similarly, with respect to rates of cancer, rates of cancer are going to change according to exposure to other forms of carcinogens, so whether people smoke, for example, or other kinds of carcinogenic exposure. That's going to affect the rates.
To be able to say you're going to look at these rates to determine whether or not this legislation is effective, measuring those rates isn't going to tell us if they are or aren't effective. That's a problem in public health in general in terms of determining causality. There are so many things influencing people's behaviour and health outcomes, to say this particular intervention causes this or that is very difficult to do. I can sympathize with the Conservatives wanting to have a measure of success, but I don't think that's possible with this kind of public health intervention.