Since when has the husband of Diana, Princess of Wales been heir apparent?
Diana: In Her Own Words: Diana: In Her Own Words is a television documentary that was broadcast on Channel 4 in the United Kingdom on 6 August 2017. Diana: In Her Own Words:  The film includes footage of the late Diana, Princess of Wales discussing aspects of her personal life, including her marriage to Prince Charles which was recorded during conversations she had with a voice coach in 1992 and 1993. Charles, Prince of Wales: Charles, Prince of Wales (Charles Philip Arthur George; born 14 November 1948) is the eldest child and heir apparent of Queen Elizabeth II. Charles, Prince of Wales:  Known alternatively in Cornwall as Duke of Cornwall and in Scotland as Duke of Rothesay, he is the longest-serving heir apparent in British history, having held the position since 1952.
1952