Mr Armthwaite and Sir Philip

Kit realizes that he is in on the plan when Armthwaite goes to ring the bell.... to alert others to their presence. She also notes that he pretends he does not know Sir Philip. Peter is unaware.

"How on earth did you guess he was in the plot?" I asked as we set our faces to the long climb up the shoul- der of Castlerigg Fell. "Because he pretended he didn't know Sir Philip personally when you started your story. He was nervous then. He didn't know how things were going to turn out and he was playing for safety. If he'd found it was
all up with the plot, he'd have gone on denying that he knew Philip. But he does. I remember his face. They've
dined at my guardian's on the same day, and I've watched them talking."