ITV1 is to screen a fly-on-the-wall documentary revealing how the very private author JK Rowling wrote her final Harry Potter book.

The channel has been granted exclusive access to the writer over the past 12 months.

Viewers will see her putting the finishing touches to Harry Potter and the Deathly Hallows, the seventh and final instalment about the schoolboy wizard.

The author has already revealed she broke down and ‘absolutely howled’ when she finished one chapter.

A Year In The Life… JK Rowling will air this autumn.

It is a coup for ITV1 as the author gives few interviews and fiercely guards her private life.

The documentary is one of the highlights of the channel’s autumn season, which will also see Harry Potter himself in a new drama.

Daniel Radcliffe will star as Rudyard Kipling’s son in My Boy Jack, with Sex And The City actress Kim Cattrall as his mother.