I took it as he came home after being in Intelligence during the war an was putting up a front for the locals whilst still being involved in the intelligence community. As long as the locals thought he was just being the dutiful son and sailing around the place aimlessly, none of them would question his actual motives for being there. It's much easier to keep your ear out for local gossip when the locals have known you all your life. An offcomeden would stand out too much and arouse the general suspicion that strangers always do.