Perhaps the definition needs changing. Living history, as a definition, obviously (to me) ends when no-one who experienced it continues to live and as EBarnacle says, is able to refute the rewriters. As the last participant in WWI has passed, it is history. It was 'living history' 40years ago, because my Grandad told me his side of it, 'stripped his sleeve and showed his scars.'
Perhaps we need some statistical definitions, like Single Account History, Multiple Account History, Popular Account History, Removed History. (Accounts from people who didn't experience it.)
Suspicious History? Massaged History? Government Sanctioned History? Fox History?