I mean, there’s a lot of books. Like. Ludicrous amounts of books. Tens of thousands of millions of books. But there aren’t a whole lot in the way of rich forests to cut down, and /seeing/ trees is rare. It’s not like we’re growing sugar cane down here. Mushrooms don’t grow tall enough to make paper from.
What are we writing on?
Well, London does still have trade with The Surface. They probably import their books, and likewise their paper.
Some of the mushrooms can grow quite large indeed, actually. (And one mushroom, I discovered by accidentally hitting the random button on one of the wikis apparently can serve as your secretary!)
Honestly, who knows what odd plant and fungal life thrive in the Neath that might serve as suitable sources for paper. Plus there are assorted animal-based paper substitutes that could be employed.
There seems to be lots of trees in Parabola. Haven’t dreamed of any lumberjacks, but who knows what people across the Unterzee gets up to? I assume that London imports just about everything from somewhere, and the worst case scenario would be that most of the paper comes from before London fell, and the rest is imported from the Surface. (Though that seems unlikely, since Surface imports are supposed to be rare.)
Not all of the Royal Bethlehem’s guests check out…
A quick search revealed that paper can be made from mushrooms - among a number of other fascinating mycological products! Given the size and plenitude of Fungus in the Neath, I don’t doubt that Messrs. Apples and Pages have much trouble in sourcing materials to be pulped, pressed and printed.
Certain aspects of FL may not be rigorously realistic simulations. The relationship between London and the Surface is not much described in what I’ve read so far. For example, whether Parliament still meets there, and if so, whether members of the House of Commons routinely return to the lands of their electorates. In which case, political assassination has a new option: kill someone just enough that they cannot return to the Surface.