But that aside I do have the question: how long has Marc known that the cave in was no accident?!?! Since 1981* ?!?!
Like the Aslan "secret", maybe it's been around forever?
When I went back and re-read it, I couldn't work out how Jonathan knew of the boarded-up tunnels, nor that they were dodgy at that one point.
But I'm more interested in him getting his hands on the Vilani Forbidden Knowledge. I'm guessing that the "bubble ships" he saw twice were pretty similar to the Ancient ship in Secret of the Ancients?