Princess Diana, Sam McKnight, and Kate Middleton.Getty Images (3) Tap Here To Add Us Weekly As A Trusted Source Add as a preferred source on Google Sam McKnight is not here for negative comments on Princess Kate Middleton's new blonde hair. McKnight, 70, who spent seven years working with the late Princess Diana as her personal hairstylist, took to Instagram on Thursday, September 4, to defend the Princess of Wales' hair makeover hours after she debuted honey blonde tresses and received negative feedback from online trolls.