I first read Natasha Pulley's Bedlam Stacks in a library copy. I liked it, but not as much as The Watchmaker of Filigree Street. Or so I thought. Still, after a while I decided to buy a copy to have on hand, knowing I would want to reread it someday. The day came as soon as I put down The Lost Future of Pepperharrow, and very glad I was to have it with libraries and bookstores now closed. I loved it on second reading! It sent me Googling Pulley, which led to two links that are worth pursuing if you are interested in the interweave of fact and fiction.
First is a pair of interviews at the Foyles bookstore website. In one question, the interviewer points to one of her more delicious inventions—luminous pollen—and asks her to say something about mixing of fact and fantasy. She answers, "Part of the idea is that I think it's a good experience in a story, to not quite know where the border between real and fantasy is. It makes the magic more magic if it might just be real." I like that kind of ambiguity, too. (It's also true that in more straightforwardly magic-is-real fantasy, it helps to make most of the concrete details as recognizable and mundane as possible).
The second link is even better for all of us in self-isolation. Pulley has prepared a terrific five-minute video lesson Writing Fantasy: How to Start. Watch it and give it a try!