Stream Postman's Knock Online Free – Watch Full Movie from Home at 123Movies. . Likeable country postman Harold Petts gets transferred from his village to London, where on his arrival he unwittingly foils a mail train robbery. Innocent in the ways of the big city, he is thought to be a member of another gang by both the train robbers and the police, who all suspect him of trying to rob the post office where he works.