I'm going to tell a story which doubtless some of you on this thread will think is made up, but I swear on my mother's life it is completely true.
I went to a little village school on the outskirts of a small town. My Year 2 teacher, let's call her Miss Pankhurst*, taught at that school for over 30 years, from her 20s to her retirement, and never married. The size of the town and the length of her career meant that she was, and still is, very well known locally, and most local people will have been taught by her, or have a child who was taught by her, or know someone who was taught by her.
When I was in my late 20s, i.e. more than 20 years after she taught me, I was on the train up to London from my home town, and I overheard a small group of people talking about Miss Pankhurst. Her actual surname is very unusual and I've never met another one, so they were definitely talking about her.
One of the men in the group said, and I quote, "I always thought it was a shame that she was a Miss. She was so lovely with the children, and very pretty when she was young. She deserved to be a Mrs, not a Miss! Not like Mrs Battleaxe**, now she was a right grumpy cow who deserved to be a Miss."
*a pseudonym
**a pseudonym for another teacher at the school who would have been known to many people in the local community
I was shocked to the core by this conversation. It really highlighted how people make value judgements about women based on their perceived marital status.
That was the day I decided to become permanently Ms. I accept that people will still make value judgements about me based on me being a Ms, but it seems like the least worst option.