The landlady seemed satisfied. She nodded, unfolded her arms, and made a slight dipping movement which might almost have been a curtsey. "Joan Kenney, widow, at your service. Will you eat, sir?"

"What have you?"

"Pottage," she said firmly.

I had by that time been in England long enough to know that pottage was a sludgy concoction produced by mixing oatmeal with the juice left over from stewing meat, something that should rightly be served to livestock but which the English seemed to find an indispensable addition to any table.

"No meat?" I asked hopefully. "It is Sunday."

"We have pottage, sir. You may take it or leave it."

Reluctantly, I said that I would take it.

"Humphrey!" she called, and a door opened beside the serving hatch to admit a young man with fair curly hair holding a dirty dishcloth in his hands. Though he was at least six feet tall and probably in his twenties, he looked first at the landlady and then at me with the blank, open face of a child eager to please, and I guessed he was probably slow-witted.

"Fetch Master Nerlarno some pottage and a pot of ale quick as you can, and don't even think of imposing on him with your idle chatter," she snapped, and Humphrey nodded furiously, with exaggerated up-and-down movements of his head as a child might, twisting the cloth in his hands as he looked at her. "He's Welsh," the landlady added darkly, as if this explained much.

While the boy disappeared to the kitchen, the woman crossed the room and leaned over the table to whisper something to the earless man, who inclined his head and nodded sagely without taking his eyes off me.

The boy, Humphrey, returned promptly with a bowl of tepid grey slurry which he slopped half across the table, and a wooden cup of beer topped with a film of grease, and stood by the table smiling energetically down at me.

"Thank you," I said, eventually, and when he still didn't leave, I wondered if I was supposed to tip him.

"Are you from Italy?" he asked, in a lilting voice, crouching so that he was at my eye level and considering me with his head tilted to one side.

"That's right," I said, poking the contents of my bowl with a piece of bread. They seemed to have congealed already.

"Say something in Italian then," Humphrey said, as if challenging me to impress him, the way a child might challenge a street conjuror. I thought for a moment.

"Non darei questo cibo nemmeno al mio cane," I said, smiling pleasantly but keeping my voice low, just in case. His eyes lit up with as much wonder as if I had produced a coin from the air and his broad face creased into a smile.

"What does it mean?"

"Oh-it is hard to translate directly. It was a compliment on your delicious food."

He leaned in very close, so that his breath was tickling my ear. He smelled overwhelmingly of onions. "I don't know Italian," he whispered, "but I do know Latin."

"Good for you," I said indulgently, expecting a string of nonsense, for it was impossible that a simple-minded potboy could truly have been educated in Latin. He nodded hard, his face serious.

"Ora pro nobis," he hissed into my ear, then drew back to look at me expectantly, proud of himself, awaiting my approval.

I felt my own eyes widen then, and fought to keep my face steady; a faint light of understanding was beginning to spread over the questions that jostled in my mind.

"That is very good, Humphrey. Do you know any more?" I whispered back. He beamed and leaned in again, but at that moment the landlady's shrill voice broke in.

"Humphrey Pritchard! Did I not tell you to leave the poor gentleman alone? Ha'n't you got work to do? He don't want to listen to your foolishness-let him enjoy his meal in peace." With this misplaced optimism, she appeared suddenly at Humphrey's shoulder, cuffed him lightly around the back of the head, and shoved him toward the kitchen; though he was twice her size, his face crumpled with guilt and he scurried away, his big body hunched miserably.

The landlady wiped her hands on her apron and forced a smile. "He wasn't saying anything, ah…offensive, I hope?" she asked, but I thought I caught a note of anxiety in her voice.

"Not at all," I said. "He was only asking if the food was all right."

Her eyes narrowed. "And is it?"

"Mm. Thank you."

She looked at me for a moment as if she wanted to add something, then nodded curtly and disappeared into the kitchen, where I heard the sound of muffled voices, hers berating poor Humphrey and his raised in protest.

Dinner was an uncomfortable affair; I forced as little of the grim stew as possible through my clenched teeth, conscious all the while of the level stare of the earless man and his cronies in the corner. I half hoped he would at least come across and confront me, perhaps explain why he looked at me with such interest or familiarity, but he remained in his seat, stirring only occasionally to lean across and murmur something to one of his companions.

I kept my eyes on my plate, my mind chasing after fragments of conversation. Ora pro nobis. Pray for us. The words written in code in the back of Roger Mercer's almanac. A prayer of intercession, a fragment of the Ave Maria or the Litaniae Sanctorum, for where else would an uneducated man like Humphrey learn Latin except from the responses of the Mass? So young Humphrey Pritchard had either overheard or taken part in Catholic liturgies. Had he heard those words through association with people he knew from the tavern? That would explain why his employer was so keen to keep him from talking to strangers. And why had Roger written out that same phrase in code? A password, perhaps, or a sign to be recognised among co-conspirators. Was the Catherine Wheel some kind of meeting place or safe house for secret Catholics-was that what my enigmatic correspondent at Lincoln College was trying to steer me toward?

I realised that I had been staring at the earless man as I contemplated this. Almost as if he had been stirred into life by my thoughts, at that moment he rose to his feet, brushed down his doublet, and called to the landlady to settle his bill.

"Alas, Widow Kenney, I must leave you for now-though it is the Sabbath, business presses as always," he announced, and I was surprised to hear that he had an educated accent. It made a disconcerting contrast with his appearance, which gave him the look of a common criminal. Once again, I had to reprimand myself for making hasty judgments on a man's manner or looks. I waited until the door had swung shut behind him before following suit. If Widow Kenney saw anything suspicious in my haste to leave, it was indistinguishable from her habitual expression, and she thanked me flatly as I threw some coins on the table and hurried out of the door, craning my neck in both directions along the street in the hope that I would still have the earless man in sight.

I was in luck; he had almost reached the top of the street by the church. Keeping again to the shadow of the buildings on my left, I told myself that this pursuit was far more worthy of one of Walsingham's agents, and I found I was relishing the drama of the moment and the rush of adrenaline in my veins.

The earless man crossed the broad street and passed under the north gate, by the church of St. Michael and the Bocado Prison. I followed him at a safe distance along Sommer Lane, past the front of Exeter College and the rear wall of the Divinity School; at one point, I had the sense that someone was following me and turned sharply, but there were only a handful of people in the street, all going about their business without apparently taking any notice of me, so I put it down to heightened nerves and kept my eyes fixed on the earless man.

At the corner of the university schools, he turned right into the narrow lane called Catte Street, where the houses stood closer together, the timber-framed upper storeys overhanging the road so that it stood in shadow, keeping the ground still wet underfoot. From the abundance of painted signs jutting out from the buildings, groaning gently in the wind, it was clear that this was a commercial street; closer inspection revealed businesses catering to the needs of an academic community: printers, stationers, makers of robes and regalia, and a number of book dealers and binders, all shuttered and closed.