My parents always received a card at Christmas from "your dad's cousin" Nancy. A few years ago I wrote to Nancy asking for help with my Family History but having no reply assumed she must have died. Try as I did I could find no Nancy on any of the birth records of any of my Dad's Aunts or Uncles.
This Saturday I received a letter from Nancy telling me about her forthcoming 90th birthday and would I send her some photos of my Dad! "oh by the way" she wrote "my proper name is Edith Annie"
Moral of the story:
never assume the info you are given is any where near the whole truth
after telling my niece this tale this morning she reminded me that she only found out my real name 2 years ago