Lee, 88, won a Pulitzer Prize for To Kill a Mockingbird, her debut novel, which told the story of a black man charged with raping a white woman in small town Depression-era Alabama, narrated through the eyes of tomboy youngster Scout.

It became an instant bestseller in 1960, capturing the imagination of thousands of readers with its heartwarming and quietly devastating narrative.

Lee first penned a manuscript for the sequel book in the 1950s, but her editor was "who was taken by the flashbacks to Scout's childhood" convinced her to write a novel from the point of view of the young Scout.

In a statement released by her publishers Penguin Random House, the novelist said she had believed the manuscript for her original book to be long lost, "so was surprised and delighted when my dear friend and lawyer Tonja Carter discovered it".

The sequel has become the most pre-ordered title on Amazon since the final Harry Potter book, the online retailer said today.

Be the first to listen to Reese Witherspoon's narration of Go Set A Watchman below.

Listen to Reese Witherspoon read the first chapter of Harper Lee's 'Go Set A Watchman'