Professor Ernst receives hate mail from natural health therapists but this doesn't bother him and despite thousands of years of evidence to the contrary, he believes herbal medicines don't work, particularly attacking Prince Charles' Duchy products.

As a teenager in Munich he was treated for hepatitis with homeopathy by a family doctor, and recovered. After he completed his medical training his first job was in a homeopathic hospital.

"The evidence 20 years ago wasn't so negative," he says. "I personally felt it might well go the other way. Of course, the assumptions on which homeopathy are based are utterly implausible, but the clinical evidence at one stage, when I started looking at this, seemed much more positive. I thought this [would be] an interesting field to investigate. Maybe there's something fundamental to discover which means it becomes plausible, if you see what I mean?"