Sergeant Alexander Blackman, "Marine A", 6ft 3in tall and ramrod straight, after being sentenced to life imprisonment, reduction to the ranks and dismissal with disgrace from Her Majesty's Service, marched out of the courtroom and from what has been his two-rows-of-medals life these past 15 years like a true Royal Marines NCO. Here was the self-discipline and professionalism that had eluded him in that moment in Helmand when, in cold blood, he shot a wounded Taliban insurgent. A man is more than his worst mistake.