If its alright for the Queen to kill Princess Di then it's alright for Harry to kill the Taliban.
However, if he killed innocent civilians, then I'm sure his mother would be turning in her grave. After all she campaigned against the landmines didn't she, god bless her. She saw that blowing innocent people up in the name of war was wrong, so if her son has shot anyone who was not Taliban, she is going to kick his ass when he goes to heaven, or wherever she is.