Imprisoned in the Castle of Saltwood (1407), Thorpe was brought before the primate, Arundel, for examination. The record of what passed between him and the archbishop is from the pen of Thorpe. He found Arundel in "a great chamber," with a numerous circle around him; but the instant the archbishop perceived him, he withdrew into a closet, attended by only two or three clerics.
Arundel: "William, I know well that you have these twenty winters or more travelled in the north country, and in diverse other countries of England, sowing false doctrine, labouring, with undue teaching, to infect and poison all this land."
Thorpe: "Sir, since you deem me a heretic, and out of the faith, will you give me, here, audience to tell you my belief?"
Arundel: "Yes, tell on."