But mentioning the travel required to produce cotton nappies kind of leads me to the conclusion that disposables are all manufactured in the supermarket or in Boots. Because, you know, they don't need transporting from anywhere first.

The study also missed out the long-life of cotton nappies, as well as all the flaws ailbhe has mentioned above. A disposable has a working life of no more than eight hours (used overnight for an older baby; the average is probably more like two). A cotton nappy has a working life that can continue for years. My mother offered me my terry nappies as burp cloths, because she still has a couple of them left - the rest have long since become dusters, floorcloths, parts of fancy dress costumes, etc.