I keep trying to write about the economics of open access to academic books via Book Processing Charges (BPCs) in a clear way. So there’s nothing really new in this post but I think I did stumble today upon a way of putting things that I’ve said before in a different and more concise fashion. If the academic “book market” was a fixed size, we could just about do a transition to open access books in the UK at some of the lower prices.