‘But I have never taught anyone . . .’ I was startled.

‘The children are quite young. The boy is nine, the girl older, about fifteen, I believe. It will not require anything very advanced. You would not need to stay for long. Slip quietly into the ways of the family, as the respectful tutor. Keep your eyes and ears open. If you discover any letters, copy them if you can. If not, at least make a note of the sender and the recipient. Once that is done you can leave – say your father is ill. Any excuse. All I need to know is whether there are letters passing through that house and who is involved.’

I tried not to show how much his account of the St Bartholomew’s Day Massacre and his calm request to spy, while acting as tutor to two Catholic children, had frightened me. I had never spent a night away from my father since we had come to England. It would be more difficult to keep the secret of my sex if I must live in another household. What if I were put to share a room with other men? Yet I could not lay this problem before Sir Francis.

‘I would be glad to serve you, Sir Francis,’ I said, ‘but I am doubtful about my capacity for this task. Besides, there is my employment at St Bartholomew’s.’ As I spoke, the words chimed in my head. What an irony that the same saint should be associated both with one of the most terrible acts within living memory, perpetrated by Christians upon fellow Christians, and also with the hospital where I worked, set up centuries before by Christian monks to serve the common people of London.

‘There will be no problem with the hospital,’ he said briskly, getting up again and moving to the chair behind his desk. The intimate nature of our conversation dwindled away, now we were separated by that great bulwark of carved oak. ‘I can easily arrange for you to have leave from the hospital. As for the other, I am very confident in your ability to carry it out. There is no need for special training. You will report when you return here, so we do not need to arrange for letters to be sent. All you need to do is carry out your duties as unobtrusively as possible, stay alert, and seize every opportunity to examine any letters which seem to be passing through the house illicitly.’

He began to write something at his desk. How, I wondered, could I combine unobtrusiveness with examining letters which would probably be kept under lock and key, in some part of the house barred to me?

‘How long am I to stay?’ I asked, realising that my choice of words might betray the fact that I had accepted that I must go.

‘A fortnight. Or at most three weeks.’

I relaxed a little. Not too long, then. Perhaps I could manage.

‘Judging by the pattern of previous visits, we expect the next to occur around the end of next week or the beginning of the following one. You will begin your service on Monday, carrying letters of recommendation from your previous employer, who will also have written in advance to say that you are coming.’

‘My previous employer?’

‘A respectable London merchant, treasurer of the Goldsmiths’ Guild,’ he smiled. ‘Do not worry, it is all in hand.’

All in hand, I thought, before I gave my consent. Had I given it?

‘What if I should be suspected? What if they should catch me looking at their letters?’

‘Then you must get out of there as quickly and quietly as you can. We’ll provide you with a horse. Make your way to my house at Barn Elms, it’s no more than five miles away.’

‘What is the name of these people?’

‘Fitzgerald. Sir Damian Fitzgerald. His wife is Lady Bridget, of Irish descent, which may explain why they may be involved in some conspiracy against this country. The children are Edward and Cecilia.’

‘And I am to instruct them in music and mathematics?’ My head had begun to whirl. I had no idea how to begin.

‘Yes. You will have some simple mathematical books you used when you were younger? I do not think they will be very skilled! As for music, I understand that both children play the recorder and the lute, the girl also plays the virginal. The girl is more talented than the boy.’

‘We no longer own a virginal, although we did in Portugal. Sometimes I play Master Harriot’s.’

‘I’m sure you will have no difficulty. If you wish, you can say that you want to concentrate on the lute to start with.’

I could see that Sir Francis’s mind was moving on to other problems. This business was now satisfactorily arranged. I stood and he held out to me a paper on which he had written the address, together with a purse which clinked faintly.

‘Come here early on Monday morning and Cassie will give you the letters of introduction and provide you with a horse. You can be there before midday. Once you have enough useful information you may return to London. I leave it to your discretion. If you have found nothing at the end of three weeks, then too you may leave. Come first to Barn Elms to see if I am there, then back to Seething Lane.’

He stood up and reached across the desk to shake my hand.

‘God go with you, Kit.’

‘Thank you, Sir Francis.’

Somehow I managed to stumble down the back stairs and out into the spring sunshine. The whole world had an unreal appearance, as though I was looking at it through a veil of gauze. I did not remember agreeing to this. How had it happened?

I wandered away from Sir Francis’s house, not paying much attention to where I was going. From the change in the light, I realised I had been with him longer than I had thought. By the time I crossed London and out beyond the city wall at Smithfield, it would be too late to go to the hospital. Some people were already heading home after the day’s work. Apprentices were putting up the shutters at their masters’ workshops. The stalls and small shops selling food were still open, their owners crying out bargains at the end of the day and the poorest citizens poking through wilted cabbages or overripe fruit near to rotting.

‘A farthing for two cabbages, goodwife!’ one stall-holder called. ‘You won’t find a cheaper price anywhere.’

The bent old crone he was trying to persuade gave a snort. ‘I wouldn’t give you a farthing for six on ’em,’ she said, turning away.

The stall-holder pretended to be shocked, but it was clear both were old hands at this game.

‘Would you take the bread out of my mouth?’ he declared dramatically. ‘And me with ten little ones at home?’

‘Give over, Matthias Starkey,’ she said. ‘You’ve two grown sons with wives of their own and a nice little wherry business between them.’

‘All right.’ He sighed. ‘Four cabbages for a farthing and you’ll beggar me.’

The woman tucked the four cabbages into her basket. The outer leaves were turning brown, but no doubt there was good food at their hearts. She was grinning as she passed me.

Before the stall-holder could put up his flap, I bought half a dozen of his little apples (a farthing), and put all but one in my satchel. As I headed north, I bit into the other. Its skin was crinkled, but it still retained some of its original sweetness.

Why was I heading north instead of west? As I reached Bishopsgate I admitted to myself that I was heading towards the Theatre. As I passed the Curtain, the play-goers spilled out into the street, heading back into London, so that I had to push my way through them. Then the crowd swelled with those coming out of the Theatre. I had timed it well. When I passed through the archway into the old convent grounds, I saw that most of the audience was gone and the doorman, after handing out playbills for the next performance, was about to go inside, no doubt to scour the playhouse for any coins the audience might have dropped.

‘Wait, please!’ I called.

The man stopped and turned round, looking slightly annoyed. It was the same man who had admitted me free on Simon’s word weeks before, but I doubted whether he recognised me.