Princess Diana's former hairstylistSam McKnightisn't holding back when it comes to addressing nasty comments aboutPrincess Kate's new blonde mane. The backlash started after Kate, 43, debuted herlightened tressesduring a visit to the National History Museum's renovated gardens. Social media users questioned whether she was wearing a wig, with some speculating about hair loss from her cancer treatments. The legendary hairstylist, 70 — who worked as the late Lady Di's personal hair guru for seven years —took to Instagramon Thursday, September 4, to slam online trolls who criticized the Princess of Wales' dramatic honey blonde makeover mere hours after she debuted the new look. "I am shocked, horrified, dismayed and disgusted by all the nasty comments about the Princess of Wales today," McKnight wrote in his fiery post. "A woman's hair is very personal to her, it's armor, defence, confidence and so much more." "I cannot believe how evil and lacking in any kind of of empathy are the comments, the majority made apparently by other women, attacking a vulnerable other young woman, who has no choice, by [way] of who she married and the role she took on, to bravely face the public," he continued. McKnight got even more passionate, writing that he's "sure" Kate "would rather be away from the public arena," and praising how "she has brilliantly and quietly, unselfishly represented our country, the soft power we still have as a nation." "Cancer affects individuals differently, but is life changing for everyone," he declared. "So FFS LEAVE HER ALONE. SHAME ON YOU." The princess announced hercancer diagnosisin 2024 and revealed she was in remission this January.