It’s always fashionable – and easy – to assume evil will come to your door, jackbooted and uniformed. In truth, evil more often comes about through the petty enforcement of the unimportant. It comes through a letter, or an investigation, or in this case, an email from a computer system. Details of the horror of the Post Office scandal are now well known. The inevitable question raised in many minds was: “how?” Thursday gave a grim insight into the answer.