I was at a book launch last week with my cousin and her husband. She recognised her old English teacher who was also attending and started chatting to her. It was obvious the woman didn't recognise her and she just smiled and made a few polite comments before going back to her friends.
My cousin was genuinely hurt. She rang me this morning and was still going on about it and how English was her favourite subject and she always got great marks.
She left school in 2002. Would anyone expect their old teachers to remember them after that length if time, if they've never seen them since?