According to the Register, Intelligent Design (ID) is on the way to the UK.
The scientific method of study is a body of techniques for acquiring and correcting knowledge. It is based on gathering observable, empirical, measurable evidence, subject to the principles of reasoning and is falsifiable, provisional and testable at the very least.
ID has no method of testing and is not falsifiable, it's therefore a principle of faith - it "holds that life on earth is too complex to have evolved on its own, without an intelligent entity guiding its path".
In short, a theory in science can be useful and the best we have until a test proves it to be wrong or a better theorem is developed - this is scientific progress. Beliefs of faith are by their very nature untestable - if they weren't they wouldn't require faith.
Now there is nothing wrong with belief in ID, though I studied Natural Sciences I certainly wouldn't argue that there are any absolute truths in science - in fact the study of science predicates against this.
It's just that ID is a matter of faith and it belongs in a RE lesson - it's not a matter of science, never was.