Props to Martin Galway to make this available to the public. I wish this were more common. I.e. writers could insist on a contractual shorter copyright period when negotiating with publishers.

Then again, I don't know how much authors earn on books after 10, 20, 30 years. It probably varies, the JRR Tolkien estate and K.K Rowling probably see still very significant income streams. It could still be a good strategy for lesser known authors.