The Duke of Cambridge has branded the decision to publish topless photographs of his wife "particularly shocking" given his late mother's battles with the paparazzi.
William expressed his sadness at the incident more than four years ago in a written statement read to a court in Nanterre, west Paris, where six people are on trial in connection with the alleged breach of privacy.
The long-lens images, taken as they holidayed in the south of France, adorned the front and inside pages of France's Closer magazine in September 2012 alongside an article about the loved-up pair entitled "Oh my God!".
William and Kate were on the terrace of a private chateau in Provence owned by Viscount Linley, the Queen's nephew, when they were photographed.
In a written declaration read in French in court by the couple's lawyer Jean Veil, William said: "In September 2012, my wife and I thought that we could go to France for a few days in a secluded villa owned by a member of my family, and thus enjoy our privacy.
"We know France and the French and we know that they are, in principle, respectful of private life, including that of their guests.
"The clandestine way in which these photographs were taken was particularly shocking to us as it breached our privacy."
The trial of six people linked to Closer and regional newspaper La Provence began yesterday.
Paul-Albert Iweins, representing Closer magazine, argued that the couple were the subject of much media attention, including the broadcast of their wedding, and that the photos did not constitute a breach of privacy and it cast them in a positive light.
Ernesto Mauri (70), chief executive of the publishing group Mondadori which produces Closer, faces one charge of using a document obtained by a breach of privacy, as does Marc Auburtin (56), who was La Provence's publishing director at the time.
Laurence Piau (50), editor of Closer magazine in France, is charged with complicity.
Three photographers face charges of invasion of privacy and complicity.
Presiding judge Florence Lasserre-Jeannin will announce the verdict on July 4 at the Tribunal de Grande Instance de Nanterre.