Ha, you will have to let me know what the book is like when you get around to reading it! I am curious as to how it differs etc, but not so much that I think I'd want to read it. It's worth a watch, though - an oddity, but interesting and well made. It's just one of those films that's purely observing its subject, really, which always feels weird when you're not expecting it. (It keeps feeling as if it's going to reveal something terrible happened to her to drive her into the fantasy, almost flirting with it in performance and questions, but as far as we ever see, nope. She was just that horrified by her own lowbrow origins!)

But everybody's very good in it, anyway.

and it's always fascinating to consider how a lot of those authors knew great success in their day and then just disappeared from posterity

Yes, I think that aspect of it is at least vaguely based on Marie Corelli.