We have a surname that has (fairly recently) become a fashionable first name - think Morgan.
DS's first name is also a name that can be a surname.
I've had two parents evenings where DS has been called Morgan in consultations in meetings and just received an email from a teacher saying that he will speak to Morgan about the issue tomorrow. This teacher has taught DS on and off for 2 years and it's a state school where teachers use pupils' first names rather than surnames.
Honestly, is it too much to ask that a teacher remembers your child's name? Particularly when the email they're replying to is entitled 'Re Marcus Morgan - 4C'.
I might reply with 'Dear Halfpenny' and see if he gets the message.
nb no real names have been used in this post.