Watch Into History on Instagram: "The incident took place during a royal visit in the early 1980s, when Prince Charles and Princess Diana were attending an outdoor public engagement. As they stood together near a railing, Charles had briefly touched a surface and appeared to have dirt or residue on his hand. Moments later, he casually wiped his hand on the back of Diana’s clothing, likely without thinking and without realizing cameras were focused on them. Diana did not visibly react at the time