In the event, my morning’s work proceeded as normal and the message arrived by the hand of a middle-aged serving man as my father and I were at home, finishing our midday dinner. It seemed that whatever Sir Francis had done, it had all been arranged with quiet discretion. I was to continue to work in the hospital in the mornings and to spend the afternoons and early evenings as a code-breaker.

That first afternoon Phelippes laid out for me several sheets containing known ciphers already in use by the conspirators in France and Spain, so that I could make my own copies. Some were quite subtle. Others so crude I found myself laughing aloud at them. Even Phelippes gave one of his small, brief smiles.

‘Indeed, a child could break them, Master Alvarez, but it saves time to have them in front of yourself while working.’

I smiled back at him. He might be a tightly controlled man, meticulous and even fussy in everything he did, but he was neither unkind nor unfriendly.

‘Most people call me Kit,’ I said, offering it as a gesture of closer acquaintance.

‘Kit, then,’ he said, with a slight bow of his head. He did not invite me to call him Thomas, but I did not expect it, for he must have been twice my age.

Once I had made copies of the captured ciphers, which he hinted had been entrusted to the same messenger who was to carry the letters from the French embassy to Chartley, he showed me two more he had compiled from the letters he had been working on since the packets had been delivered. These were complex and I had to admire his skill in breaking them.

After that he gave me a packet containing ten sealed letters and showed me how to lift the seal with the fine blade of a knife so that the paper was neither marked nor torn. That way Arthur Gregory would be able to reseal them invisibly. And so I set to work on the undeciphered letters he entrusted to me. When I completed the first, which was in Spanish, and had made a fair copy in both Spanish and English, I carried my work over to Phelippes like a nervous schoolboy hoping for his master’s approval. The letter had been written in one of the known ciphers, so it had not been a difficult task, but I had completed it quickly and hoped for praise. However, Phelippes merely scanned the contents quickly, indicated where to place the original and the two transcriptions, and went back to his own work.

A little disappointed, I sat down and lifted the seal off the next letter. However, I chided myself, I must not expect praise for every task I completed, like an anxious child. This was merely Phelippes’s daily work, no more notable for him than applying ointment to a burn would be for a doctor.

By the time he dismissed me, half an hour before curfew, I had transcribed and translated six of the letters and felt satisfied with what I had accomplished. One of the letters had run to six pages, enumerating plans for Spanish invasion troops, but as it had been written eleven months earlier it hardly had much relevance now.

I did wonder whether it was worth all the trouble of deciphering documents that were so out of date, but I supposed there might be some grain of information to be found in them – the name of a conspirator unknown before or promises of support from some traitor at home which must be investigated. Somehow I had always imagined that the activities of Walsingham’s network, shrouded in mystery and whispered gossip, must be as exciting as storytellers’ tales of adventurous derring-do. It had not occurred to me that much of it took place in cramped rooms hunched over ill-written scribbles which must be de-coded symbol by painful symbol. Yet I was beginning to understand that battles may be won and nations protected by just such quiet labour undertaken by anonymous men.

My father had accepted that I could not discuss with him the secret nature of my work at Walsingham’s house, but he was concerned for my physical well-being. When I returned that first evening I was exhausted from the demanding work by candlelight, for the winter dark had come down early. As well, I was hungry, for I had eaten little at midday, from sheer nerves, and I had been given nothing to eat or drink while I was with Phelippes.

‘You must not let this work undermine you,’ my father said. ‘Did they not even give you to drink?’

I shook my head and wiped my lips with the back of my hand. I had drunk deeply from a pot of small ale and felt the better for it.

‘We were so busy.’ I found I was making excuses for my new task-master. ‘There was no time to eat or drink. Master Phelippes took nothing either.’

My father set down a plate of mutton seethed with barley and onions in front of me. ‘Eat,’ he said. ‘Your body is still young and needs nourishment. If this is to be the pattern of your days, you must make sure to eat well at noon, or you will over task your strength.’

I said nothing, but smiled at him and fell upon the food, realising just how hungry I was. He sat down opposite me with his own plate and began to eat, while watching me closely.

‘You cannot talk about your work, that I understand, but there is nothing dishonourable in it, is there?’

I swallowed a large mouthful and shook my head. ‘No, Father. It is just code-breaking documents concerned with the safety of the nation. You would think it honourable. We may not be English ourselves, but this is our home and the safety of England matters as much to us as to any Englishman.’

He nodded his satisfaction and poured more ale for me.

That first day established the pattern of my life for many days to come. Hospital work in the morning, a substantial meal at home, then the walk across London to Seething Lane and work in Phelippes’s office until after dark and the walk home. I did not much enjoy that walk home alone through the dark streets of London and kept to the busier ways, where substantial houses and business premises kept torches alight beside their doors. The narrow unlit alleyways and closes were unsafe even by daylight. After dark they were treacherous with cut-purses and worse. My father had given me a fine Spanish dagger of his own to wear at my belt, although I am not sure how well I would have been able to defend myself, had I been attacked.

The tottering stacks of accumulated letters gradually diminished until one evening we finished the last of them. Phelippes stretched his arms above his head and flexed his fingers. My own fingers were blackened with ink. I would need to scrub them hard with pumice stone before attending any patients in the morning.

Arthur Gregory came in to collect the last half dozen letters.

‘The courier came earlier, Master Phelippes. Shall I send the boy for him?’

‘Aye.’ Phelippes removed his spectacles and rubbed his eyes, as he often did when he was tired.

While Arthur went to find the messenger boy to fetch the courier, I tidied my desk, throwing my rough papers on the fire and stirring them with the poker until they were entirely consumed. The fair copies of all our transcriptions would be placed in Sir Francis’s files under lock and key, while no rough draft must be left lying about where it might find its way into the wrong hands. Though I knew Phelippes locked his office every night, he, like Sir Francis, was obsessed with security and secrecy.

‘Will you want me tomorrow?’ I asked, not sure what my position was to be, now that we had worked our way through those great stacks of letters.

‘No, no. There will be no need for you to come tomorrow.’ He stood up and began to straighten his own desk. Like me, he burned his working papers, which were covered with his minute handwriting in ruler-straight lines. I have never seen such small writing at any other time in my life. I could barely read it.

‘When I have need of your help again, I will send for you, Kit. There will be more work, certainly, but – I hope – never such a mountain as we have just tackled. I thank you for your help.’