His face had gone very white and he laid his hand on my arm.

‘This is a very dangerous enterprise, Kit.’

‘It may be that the Spanish garrison will not admit me at all. Or if they do, I may not find Titus Allanby. He may not even be there.’

‘And how do you expect to leave, in company with another? They will not allow you to walk out of the gates.’

I explained about the house with the low garden wall. ‘Look, you can almost see it from here.’

As usual we were standing on the foredeck, and I pointed up at the citadel. ‘There, off to the left of the town walls. Can you see where it bulges out a little, just before it turns round to the south? That is the garden.’

He screwed up his eyes and shook his head. ‘Nay, I can’t see it. But I will keep a watch on that part of the wall and send up my prayers for you.’

I rose before dawn the next morning and was taken ashore over the dark waters of the harbour. The birds on land were already awake and singing. On a post at the end of the quay a cormorant watched us come alongside, and only raised itself lazily into flight as I stepped ashore. I wore nothing which would identify me as coming from the English invading force, merely my usual somewhat nondescript doublet, breeches and hose, with my physician’s satchel. Before approaching the fortified main gate of the citadel, I took care to advance in a roundabout way, having first taken the precaution of checking that the soldiers in our camp had received the order not to shoot me.

While I was exploring the area around the citadel during the previous few days, I had noticed that there was a postern gate at the top of a precipitous path which descended to the sea, not to the main harbour but to a narrow bay on the opposite side of the island on which the new castillo stood. Even as I had watched from the higher ground early yesterday morning, I saw a pinnace pulling away from the end of the path leading down from the postern, where there was a wooden jetty. So it was evident that the garrison was not entirely cut off. Supplies were being brought in by night. Our armaments were inadequate to take the citadel by force and there was clearly no possibility of starving them out while they could be supplied thus clandestinely. The siege was as pointless as I had always supposed.

I had given some thought as to how I could approach the fortress without being shot on sight. It would be obvious to any watchman that I was unarmed, but a nervous sentry might not care to take the risk. Shoot first and ask questions afterwards. Therefore I had provided myself with a large square of white cloth, the universal emblem of peace, and could only hope that the Coruña garrison would interpret it accordingly. I felt physically sick as I stepped on to the broad street leading up to the main gate of the citadel. At that moment my plan did not seem like courage but an act of gross stupidity. My heart was pounding so hard it that it dulled my sense of hearing. I could, I suppose, have abandoned the search for Titus Allanby as impossible and stayed aboard the Victory until Drake and Norreys decided to leave Coruña, but at the back of my mind I was haunted by the memory of Mark Weber.

Last year, Walsingham had sent me in search of one of his agents, Mark Weber, who had gone missing in Amsterdam. I had found Weber, it was true. But he was already dead. Although by all the signs he had probably been killed before ever I reached Amsterdam, yet I could not quite shake off the feeling than somehow, if I had been able to find him sooner, he might still be alive. I did not want the same fate to befall Titus Allanby. He had reported to Walsingham that he feared he might have come under suspicion. Had he still been in the town when we arrived, he would probably have contrived to reach one of the ships. Since he had not, it seemed that what the old woman had said must be true, that he had been summoned to the garrison before we reached Coruña and was still there. That summons might have a quite innocent explanation. Or it might mean that the officers of the garrison were indeed suspicious and wanted him under their eye, where he could not pass information to England.

I took my stand some yards from the gateway, holding up my white cloth. There was no reaction at all from the fortress. No figures appeared on the walkway above the gatehouse. No cannon was swung down to take aim along the street. No musket or crossbow was thrust out from one of the firing positions on the ramparts.

I took a step forward.

Nothing.

Two more steps. Three. Four.

Suddenly there was the twang of a crossbow, and a quarrel, fast and deadly, whined over my head like a monstrous bee. Instinctively, I ducked, but far too late if the bolt had been aimed at me. Whoever was shooting had aimed deliberately over my head. It was a warning.

I stopped. What should I do? If I advanced further, the bowman might aim lower and I would have no chance. I wore no armour. A crossbow bolt at this range would pierce me from breast to back and I could not live more than a few minutes. It was too far away to shout, to explain why I had come. I could turn tail and walk away. Or I could go on.

Holding my white cloth above my head, I went on.

Another bolt shot over me and this time I thought I really would vomit, but I kept walking in a kind of numb trance, until I was near enough to make myself heard.

‘Don’t you see my white flag?’ I shouted. ‘I am a doctor. The English have allowed me to come through.’ This time I was careful to speak in highly educated Spanish, allowing no trace of a Portuguese accent to creep in. ‘I have come to help tend the wounded.’

It was a dangerous ruse, but I was counting on that disorganised and panicked rush to the citadel when they had first seen El Dracque’s standard. There might have been one resident physician in the island fortress before the garrison abandoned it, but had he fled here with the soldiers? There would have been no time to organise adequate medical care. If I was lucky, there might not even be a single physician with the soldiers.

No one answered, but there were no more shots over my head as I covered the rest of the distance to the gate. Confronted by the massive double doors of the gatehouse I stopped and waited, hoping that someone was fetching an officer. At length, a voice called from above. I stepped back and tilted my head. A man leaned over the parapet, wearing the distinctive helmet of a Spanish soldier, with its almond-shaped crown and curled brim.

I repeated what I had said before, holding out my arms on either side, so that he could see that I wore no sword and carried no musket.

Even at this distance his suspicious frown was clear to see, but he did not immediately dismiss me. I could feel the pulse beating in my throat and I had to concentrate hard not to let my hands tremble.

‘Very well, we’ll have a look at you.’

After a moment, the wicket gate opened in one of the heavy doors and I was allowed through. I was inside. It might not be so easy to get out again.

I tucked my white rag into my belt and followed the soldier who gestured to me to cross to the base of a stair which must lead up to the wall-walk. A man was coming down, the man who had spoken to me. He looked me up and down.

‘You are over young for a physician.’

At nineteen I no longer considered myself so very young to be practising medicine, but I suppose my smooth cheeks made me look younger. I laid my hand on the buckles of my satchel. Immediately the other soldier leapt forward and grabbed both of my arms from behind.

‘I was merely going to show you the implements of my calling,’ I said mildly. I must remain calm and pleasant, and show no fear.

The officer – for he was clearly an officer – stepped forward and unbuckled the straps of my satchel himself. He poked about amongst the contents, then stood back and nodded to the soldier.