Katherine Waterston: "They don't tell us anything probably because they're so afraid we're going to gossip about it. Just last week we had this fan event in London and J.K. Rowling walked onto the stage. They didn't even tell us she was going to be there."

"Then she told the audience that we were going to make a fifth film. We thought maybe we'd make four. I was sitting there on stage and all the actors had their jaws on the ground, and I was just thinking maybe there was some kind of stem cell lab in Switzerland that I could go to dip my whole body in to stay well preserved to get to the fifth film.

"I just imagine me and Eddie Redmayne with our walkers and wands trying to stop a bad guy."