What roused him was the sound of trampling feet on the stairs outside, and the voices of persons ascending.

He lay for a few moments in the darkness, which the few smouldering embers of the dying fire scarcely served to illuminate; and then in a sudden access of alarm be sprang to his feet and made for the door.
If escape had been in his mind, he was too late.

Already the door was burst open.

A flood of light from a couple of lanterns dazzled his eyes for some moments, so that he could only see that several men were in the room, and a stern voice exclaimed, "That is the man! Seize him!" Then he knew that his hour had come, and that he was arrested.
Next minute he saw clearly, and found himself confronted by the proctors of the university, who regarded him with stern faces.

Who had given them warning that Garret had returned to Oxford has never, I believe, been known--at least there is no mention of this made in the history of the known facts.