Prince William and Prince Harry speak about the mother side of Princess Diana for the FIRST TIME [VIDEO]

Get those tissues ready because this is going to be an emotional read. As Princess Diana's 20th death anniversary nears, more insights into the Duke of Cambridge's life are emerging in the press. Some shocking reveals were made through Diana's secret tapes and Prince Harry also came forward to talk about life after his mother's death.

However, this will be the first time that Diana's two royal children, Prince William and Prince Harry have sat down together to discuss their mother since her death. Featuring in a documentary titled: Diana, Our Mother: Her Life and Legacy, the two princes will become candid about Diana. The first trailer of the docu has just released and let us warn you, it could be a tear jerking experience.

The duo said this was the first time the two have actually spoken about Diana as their mother and not the Princess. The brotherly bond is evident as William and Harry are going through some archived photos.

Stopping at one featuring just William and Diana, the elder brother reveals, "Believe it or not, you and I are both in this photograph, you're in the tummy."

Viewers also get to see some never-before-seen photos of the three – Diana, William and Harry. William said Princess Diana liked to have fun. "But she understood that there was real life outside the Palace walls," he shared.

"She was one of the naughtiest parents," William adds as the video features some special moments from the past.

Through the short video shared, the royals teased that there will be many intimate details about their relationship with their mother that will surface through the documentary.

As the video ends, one could sense Prince Harry holding back his tears as he says, "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," Prince William adds, "She smothered us with love, that's for sure."

The documentary is scheduled to air on ITV in Britain and on HBO in the US later this month.

Watch the trailer here: