My niece and nephews called me 'Auntie M' when they were young; now that they are well older (all 30+) they call me Auntie M or just M; I don't mind which. All my children's friends and friend's children called me by my Christian name, my choice. Most of the tradesmen I've known for years use my Christian name apart from the garage mechanic (who I've known for years) who, despite being invited to use 'M', persists in calling me Mrs D.
What I cannot bear (and is probably quite illogical) is getting mail addressed to me by Christian name, instead of Mrs. M. D. Likewise marketing emails from companies I've bought stuff online from. So now, when I'm ordering online I fill in the 'forename' box with just 'M'. At least it guarantees that letters and parcels are, in my eyes, correctly addressed! It's a bit odd getting emails starting 'Dear M' but I can live with that 
I worked in a local secondary school for 13 years pre-retirement. All female teachers were universally addressed as Miss, all the male ones as 'Sir', regardless of marital status. Children were often quite unable to tell me the surname of any of their subject teachers...