Although little known in Britain, Doris Kearns Goodwin is one of the American public’s favourite popular historians. Her career began in bizarre circumstances: as a young White House intern in the Lyndon Johnson years, she became a kind of muse to the troubled president, who poured out his social and political anxieties in a string of late-night (though chaste) encounters. That gave her the material for her first book, and since then she has become the epitome of that peculiarly American breed, the non-academic ‘presidential historian’.

Goodwin hardly needs any help to shift books, but last year she got it anyway when Barack Obama publicly commended her latest bestseller and announced that he was using it as inspiration as he put his government together. At the time, this sounded like spin: praising the book