Here's a curly one.
I have a digital edition, prepared by me, of Sir Malcolm Campbell's novel "Salute to the Gods" (1934).
Campbell died in 1948. However, so far as I can tell, the book with written in collaboration with an un-attributed ghost writer who was, it seems, James Wentworth Day. Wentworth Day (if indeed he was the ghost writer) died in 1983.
I assume that in this case the original copyright was always Campbell's, and that Wentworth-Day was acting as an employee of Campbell's for the novel.
Question: Is this book now in the public domain in life + 50 countries?
I know it is in Australia, assuming Campbell was sole copyright owner, because there was no back-dating when Australia went from Life +50 to Life + 70, ie, anything already in the public domain at the time of the change to life + 70 stayed in the public domain. This book was in the Aust Life + 50 PD at the time of the Aust copyright change.