On the top floor of Random House's offices in London, the world's number one thinker — according to Prospect magazine's annual poll — walks in from the roof terrace and shakes my hand. Richard Dawkins is a trim 72-year-old with one of those faces that, no matter the accumulation of lines, will always draw the adjective "boyish."

There's a smoothness to the way he carries himself — a touch of the Nigel Havers — that could no doubt be construed as an arrogance befitting his intellectual status, but in conversation he is restrained, even hesitant, and faultlessly modest throughout our interview.

Perhaps the renowned evolutionary biologist and the world's most famous atheist was feeling especially cautious. The day before I met him he had become embroiled in a Twitterstorm, which grew into a broader media monsoon, after he had tweeted the following: "All the world's Muslims have fewer Nobel prizes than Trinity College, Cambridge. They did great things in the middle ages, though."