David McCullough

With the Truman book, I wrote the entire account of his experiences in World War I before going over to Europe to follow his tracks in the war. When I got there, there was a certain satisfaction in finding I had it right - it does look like that.

There are clearly many good politicians who are guided by religious belief, so the mix can work. But there's a line to be drawn. It would be hugely dangerous for a country's laws to be set by the scriptures, and particularly those of the expansionist religions.

I am a part of the old school where I feel that purity of the language should be retained. But English is a constantly evolving language where new words are being added to the dictionary, so I don't see any harm in experimenting with the language. Only poor editing standards need to be improved.