Prince Charles once scolded Princess Diana for donning black dress to their first royal engagement

Prince Charles once reportedly  criticized Princess Diana for wearing a black  dress to their first royal engagement as a betrothed couple.

Members of the British royal family abide by many style rules and protocols.  They reportedly  wear black clothing during periods of mourning.

Diana and Charles reportedly argued over the dress ahead of their appearance in a fundraising concert at Goldsmiths Hall, London on March 9, 1981.

Diana shared the details about the incident during a secretly recorded interviews in 1991 for her biography "Diana: Her True Story" by Andrew Morton, which was revised in 2017 and titled "Diana: Her True Story — In Her Own Words."

"I remember walking into my husband-to-be's study, and him saying: 'You're not going in that dress, are you?' I replied: 'Yes, I am'. And he said: 'It's black! But only people in mourning wear black!'" Diana reflected.

"I thought it was OK because girls my age wore this dress. I hadn't appreciated," Princess  Diana revealed in the secret tapes. 

Prince Harry's mother was only 19 when she got engaged to Prince Charles, 32. She was told to follow the same fashion trends as the other royals do.

Diana reportedly rocked a black off-the-shoulder Christina Stambolian gown on the same evening that a documentary aired on national television in which Charles admitted he had been unfaithful to her.