HBO documentary Films has released the first official trailer for the upcoming documentary Diana, Our Mother: Her Life and Legacy. The tribute film, created to commemorate 20 years since her death, will see her two sons – Prince William and Prince Harry – offer an insight into the life of the British princess as a parent. "This is the first time that the two of us have ever spoken about her as a mother," said Prince Harry, before continuing, "She was one of the naughtiest parents. She was our mum. She still is our mum. And of course, as a son I would say this, she was the best mum in the world. She smothered us with love, that's for sure." 

While no specific dates have been confirmed from HBO, Diana, Our Mother: Her Life and Legacy will air on television later this month. In other film news, watch the trailer for the Hugh Jackman-starred film The Greatest Showman.