Thanks, Sarushka - I knew it was Imperial Majesty but I wasn't thinking for some reason.
I was wondering myself about those not in the nobility and how one would address the old lady down the street or the parents of a friend.
We here would say Mr or Mrs or in some cultures "Miss" even though the lady was married. In the deep South in the US ladies are called Miss Becky (or whatever) as a courtesy even when they are 90!! It is a sign of respect. I have a dear friend who still calls my mom Miss Isabell even though my mom is 88 and has been a widow for over 38 years.
In Russia, if one didn't have a title (Highness) or position (professor) or military rank (Colonel) how would a younger person address them? I know that those on fairly equal footing would use the given name and patronymic.
Dr Botkin, for example, called Nicholas Your Imperial Majesty, but Nicholas would call him Yevgeny Sergeivich. But I think, and I could be wrong, that Dr. Botkin's other patients probably called him Dr. Botkin.