The unprecedented documentary will be built around interviews with The Duke of Cambridge and Prince Harry, both of whom talk openly and in depth about their mother and how her influence has shaped their lives.

Their Royal Highnesses will also offer their perspective on the Princess' unique contribution to public life, including her charitable and humanitarian work. Areas including landmines, child bereavement, homelessness and HIV and AIDS, will be explored.

It will also include individual contributions from many key figures in the Princess' life and new archival material. Through the personal and intimate reflections of her two sons and of her friends and family, many of whom have never spoken publicly before, the film will offer fresh and revealing insights into Princess Diana, an iconic figure who touched the lives of millions.