@TheSandman so it sounds like your situation is different to the hypothetical Mary Elizabeth "Lizzy" Jones situation.
Correct me if I've misread, but it sounds like you were born "Jeremy Smith" and, 35 years ago, decided to be known as "Kevin Smith". You changed your name everywhere except with your doctor and the Inland Revenue. Presumably Scottish law would have allowed you to do this, one way or another, deed poll or not. But you didn't, therefore those people still think you are called "Jeremy".
My grandmother was in the "Lizzy" situation in hospital, and yes, they should have called her "Mrs Jones" instead of presuming on "Mary". She could then have invited them to call her "Lizzy" if she so wished.
However, for her the displeasure was from being addressed informally. For you, it seems the displeasure was specifically around the use of a name that you dislike being called, even though they had no way of knowing otherwise. That's more like me getting married, changing my surname but not letting the doctors know, then getting upset that they call out for "Miss Symonds" instead of "Mrs Johnson".