Princes William and Harry released new photos from their mom's private collection as part of a tribute to Princess Diana on the 20th anniversary of her death.

Princess Diana and Prince Harry
Credit: Georges De Keerle / Getty Images

The next two photos show the royal brothers dressed up like British police officers and Princess Diana holding baby Harry on the Royal Yacht Britannia. Prince William took the photo of his mom and brother.

The tweeted photos coincided with the opening of a new exhibit at Buckingham Palace that features more family photos in a display, much of which sits on top of the desk Princess Diana used at Kensington Palace. Also included are some of her prized belongings, like her ballet shoes and a collection of cassette tapes (including albums from Elton John and George Michael). The exhibit closes October 1.

An HBO documentary, Diana, Our Mother: Her Life and Legacy, which aired last night, also commemorated the late princess, who was only 36 years old when she died. In the film, William and Harry shared memories of their mother. "Our mother was a total kid through and through," Harry said. "When everybody says to me you know, 'So she was fun? Give us an example,' all I can hear is her laugh in my head, and that sort of crazy laugh of where there was just pure happiness shown on her face."

"One of her mottos to me was, 'You can be as naughty as you want, just don't get caught,'" he added. "She was one of the naughtiest parents."

William was only 15 and Harry 12 when Diana died, and in the documentary the brothers also both expressed regret that they rushed their last phone call with their mother. Prince William said they had been "running around, minding our own business, playing with our cousins and having a very good time" and were in a rush to say "goodbye, see you later, can I go off?"

While we understand the princes' regret, we hope they also know they were just kids being kids, and that their mom likely didn't feel the least bit slighted. Based on the new family photos being shared, it's clear the bond between mother and sons was strong.