Although it is a formality, the literal meaning of the greeting is to wish someone good fortune for a specific period of time. Telling a British friend, over the phone, to have a good day is therefore unlikely to be effective, as his or her day is likely already coming to a close. “Good evening” would be more appropriate in that case.
Miss Manners notes that in addition to the logic in offering wishes for a good evening, it provides an opportunity for you to recognize that you are aware you have interrupted dinner — something you would not have done if the subject of the call were not so urgent.
Dear Miss Manners: We are fortunate to have a close-knit group of about seven families ready to help one another in times of crisis. As is common in any such group, our family feels closer to some families than to others.
Family A, we are very close to. We feel comfortable sharing personal information and seeking advice from each other.
Family B, we are not as close to. Our relationship is cordial and formal, but can't be described as deep.
Wife of Family A doesn't like to discuss her health much. When she had surgery, only our group of seven families was told about it. Later, I came to know that Family B is discussing A's health condition with others. When a family outside of our group called us about A's health, we pretended ignorance and changed the topic.
Initially, we ignored this single instance of news-leak, but we have come to know that Family B is spreading the news to many others. We understand that their intentions are good, but they need to use a little more discretion.
Should we just ignore this, or should we take some action to prevent future leaks, thereby respecting Family A's preference for privacy? For example, should we advise our close friends (Family A) to gently remind Family B not to not discuss A's health with others? Or should we call Family B directly and advise them to use more discretion?
You are asking how to correct another person’s manners — which would be impolite — without being impolite. As your motivation is the laudable one of sparing Family A’s feelings, Miss Manners will assist you.
Say nothing to Family A. Doing so would be to gossip about — and criticize — the behavior of Family B, to hurt Family A (who were presumably unaware of what was occurring) and would not resolve the problem.
Strike up a conversation with Family B and weave in a story or two demonstrating Family A’s reticence to discuss health matters openly. This is known as dropping a hint.