A letter written by a sixteenth-century merchant has come to define the image of the doomed teenage heroine Lady Jane Grey. The description it gives of the slight redhead being processed to the Tower of London as Queen is quoted in biographies, used by scholars to argue the merits of possible portraits of her, and included in bestselling novels to add a dash of authenticity. But the letter is a fraud whose centenary falls this year.

The faking of historical records has gone on for almost as long as history has been written. Usually it is done to disguise the past, sometimes for financial gain, and it is occasionally a mixture of the two. Over the last century we have seen several memorable hoaxes from the supposed love letters of Abraham Lincoln, published in the Atlantic Monthly in 1928, to the Hitler Diaries, endorsed by Stern magazine in 1983. These documents were accepted as authentic for weeks ...