No, she was right-handed. Regarding her sons, Prince William is a lefty, whilst Prince Harry is right-hand dominant. read more
While the Duchess of Cambridge is right-handed, along with the Queen and Prince Charles, there is precedence for left-handedness in the Royal Family. Queen Victoria, King George VI and the Queen Mother were all left-handed. read more
Princess Diana was also right-handed (though her father John Spencer was left-handed so there are plently of left-handed genes floating around). Prince William has been openly left-handed from an early age, but his brother Harry is right-handed. read more