Britain's Prince Charles, Prince of Wales, with his wife Princess Diana,taking their newborn son Prince William, as they left St. Mary's Hospital, Paddington, London, June 22, 1982. (AP Photo/Staff/Redman)

Britain's Prince Charles, Prince of Wales, with his wife Princess Diana, holding her newborn son Prince William, as they leave St. Mary's Hospital, Paddington, London, June 22, 1982. (AP Photo/Staff/Redman)

(FILES) A file picture take on July 29, 1981, shows Britain's Prince Charles (L) and Lady Diana, Princess of Wales, on their wedding day at St Paul's Cathedral in London. Prince Charles said Tuesday November 16, 2010, he was "thrilled" at the engagement of his eldest son Prince William to his long-term girlfriend Kate Middleton, adding: "They have been practising long enough." AFP PHOTO/STR/FILES

A combo picture show Princess Diana (R) posing in her wedding dress on 29 July 1981 and Kate, Duchess of Cambridge and her husband Prince William during their wedding ceremony at Westminster Abbey on April 29, 2011 in London. AFP PHOTO

Combo picture shows Britain's Prince Charles kissing Diana, Princess of Wales during their wedding in London on July 29, 1981 and (up) Britain's Prince William kissing his wife Kate, Duchess of Cambridge on the balcony of Buckingham Palace on April 29, 2011, in London. AFP PHOTO

Combo picture shows Britain's Prince Charles kissing Diana, Princess of Wales during their wedding in London on July 29, 1981 and (on right) Britain's Prince William kissing his wife Kate, Duchess of Cambridge on the balcony of Buckingham Palace on April 29, 2011, in London. AFP PHOTO

Prince William (C) and his wife Kate, Duchess of Cambridge, walk down the aisle of Westminster Abbey after their royal wedding in central London on April 29, 2011. AFP PHOTO/ POOL/ ANTHONY DEVLIN

A combo image showing the wedding of Lady Diana, Princess of Wales with Prince Charles of Wales at St Paul Cathedral in London on July 29, 1981 and an image showing Kate Middleton standing at the altar with her husband to be Prince William at Westminster Abbey on April 29, 2011. AFP PHOTO

This photo composition compares the bride's arrival the wedding of Prince Charles, Prince of Wales and Diana, Princess of Wales on July 29 1981 with that of Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge on April 29, 201.1 Prince Charles de Galles Mountbatten-Windsor; Prince William de Cambridge; Princesse Lady Diana de Galles;Princesse Catherine Elizabeth (Kate) de Cambridge Middleton

This photo composition compares the kiss on the balcony of Buckingham Palace following the wedding of Prince Charles, Prince of Wales and Diana, Princess of Wales on July 29 1981 with that of Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge on April 29, 2011 Prince Charles de Galles Mountbatten-Windsor; Prince William de Cambridge; Princesse Lady Diana de Galles;Princesse Catherine Elizabeth (Kate) de Cambridge Middleton

This photo composition compares the bride and groom leaving in an open carriage following wedding ceremony of Prince Charles, Prince of Wales and Diana, Princess of Wales on July 29 1981 with that of Prince William, Duke of Cambridge and Catherine, Duchess of Cambridge on April 29, 201.1 Prince Charles de Galles Mountbatten-Windsor; Prince William de Cambridge; Princesse Lady Diana de Galles;Princesse Catherine Elizabeth (Kate) de Cambridge Middleton

Keine Archivierung! +++ ARCHIV: Prinz Charles und Lady Diana Spencer posieren am Buckingham Palace in London, Grossbritannien, nach der offiziellen Bekanntgabe ihrer Verlobung (Foto vom 24.02.1981). Dianas Verlobungsring steckt seit Oktober 2010 am Finger von Kate Middleton. Vor genau 30 Jahren, am 23. Februar 1981, praesentierte der damals 32-jaehrige aelteste Sohn der Queen seine 19-jaehrige Verlobte Daina. (zu dapd-Text) Foto: Ron Bell/AP/Pool/dapd

This is a 1984 photo of Princess Diana with sons Prince William, foreground, and Prince Harry. (AP Photo)

(FILES) A file picture taken on April 25, 2014, shows Britain's Catherine, Duchess of Cambridge, with her son Prince George at the Defence Establishment Fairbairn in Canberra, Australia. Prince William and his wife Kate are "very pleased" to announce that they are expecting their second child, Kensington Palace said on Monday September 8, 2014. AFP PHOTO / SAEED KHAN/FILES