First we need to determine what will constitute the right couple. What is your interest in this man? Is he an ancestor, in which case, which of his children are you descended from, what other children did he have, have you found their births and marriages, what clues did tbey give about their parents etc? Or alternatively, is he a sideline, perhaps you are descended from a sibling of his, and found Johns christening and thought you would see what became of him, in which case what else can you tell us about his wider family, his marriage etc.
It is quite difficult to work with just an 1841 census for an apparently single person, and an 1851 census for someone who on the face of it appears to be a different man, without knowing much about the person we are actually looking for!