The princess met the leader during a private visit to South Africa in March 1997, just five months before her death. As soon as Prince Harry spotted a photo of their meeting, he was focused on finding out more about his mother's time in the country.
Gazing at the photo of them together, the Prince said, "Happy smiles, big smiles."
Verne Harris, director of the Nelson Mandela Foundation, said, "The prince was drawn to the picture of his mother, he went straight to it when he walked through the door. He wanted to know when it was taken."
During his time at the offices, Harry also met with Nelson Mandela's widow, Graca Machele. He held the the statesman in high esteem and it emerged he marked Nelson's death by planting the South African flag at the South Pole.
Harry presented Graca with a picture of the moment he planted the flag soon after Nelson's death on Dec. 5, 2013. The prince was trekking in the South Pole as part of the Walking With the Wounded South Pole Allied Challenge when the leader died, while his brother Prince William and the Duchess of Cambridge were watching the London première of Nelson Mandela: A Long Walk to Freedom and were told the news as the movie ended.
It was the prince's final day of engagements in South Africa, and ended a week-long trip that saw him carry out a number of tasks including opening his charity Sentebale's new children's centre in Lesotho, playing tag rugby with a group of children in Durban, and joining the fight against poaching at Kruger National Park.