It is hard to research history's bit-players - by their peripheral nature they leave little behind. But for her biography of Louis XIV's mistress author Veronica Buckley hit upon a startling, apparently unmined source: the secret diaries of the Sun King himself.

The journals, writes Buckley in her book Madame de Maintenon: The Secret Wife of Louis XIV, were only found in 1997, some 282 years after they were written, "a packet of yellowed papers, wrapped in string and sealed with faded red wax" hidden "inside a heavy old chest in a Loire valley manor house".

Buckley had her first biography, of Christina, Queen of Sweden, published to great reviews in 2004. Born in New Zealand, the author studied in London and Oxford, and now lives in Vienna.
To construct her latest biography, she quotes snippets from these journals throughout, and reproduces one section at length to describe a typical day in the life of Le Grand Monarque.

There is just one problem: Louis XIV did not keep a secret diary.

Or if he did, no one has yet found it.

What Buckley quotes is in fact the work of François Bluche. In 1998 this French academic decided to imagine what the king's journals might have been like, by piecing together information gleaned from myriad historical documents. The result was a book, Le Journal secret de Louis XIV, which Buckley got hold of and used as a primary source.

It is a mistake now costing her publishers dear, as they postpone the biography's launch by two months while they correct the offending passages. Due out on May 5, it will now be available in July. According to Bloomsbury, this is to give them time to "tip in" pages - pulping the offending pages, in effect, and glueing in new ones. A Bloomsbury spokesman would not say how many copies were affected, but it was "in the thousands"....