That is the second time you have quoted that, Iains. I didn't bother pointing it out last time, but it is not an *article* in the Lancet (which would be subject to detailed assessment before it appeared): it is 'Correspondence', which is not subject to anything like the same scrutiny. In effect, like a letter anywhere, it is the opinion of the author(s), not the result of a formal study. So presenting as 'from the Lancet' is somewhat misleading for the unwary.

He is entitled to his opinion, of course, and as an epidemiologist Professor that opinion carries more weight than yours or mine. But it does not carry more weight than other epidemiologists who disagree.