I try to say cheerfully: ‘No, no, Izzy . . .’ when there is a scream of wind that takes my breath away. Howling like a whistle, like a banshee, the wind pours out of the darkened sky, the boat heels over and the sea beneath us suddenly bows up and throws us up towards the clouds that split with sickly yellow lightning.

‘Close the door! Shut her out!’ Izzy screams as the boat rolls and the double doors to the cabin fly open. I reach for them and then stand amazed. Before the cabin is the prow of the ship and beyond that should be the waves of the sea. But I can see nothing before me but the prow, rising up and up and up as if the ship is standing on its stern and the prow is vertical in the sky above me. Then I see why. Beyond the prow is a mighty wave, towering as high as a castle wall, and our little ship is trying to climb its side. In a moment the crest of the wave, icy white against the black sky, is going to turn and crash down on us, as a storm of hail pours down with a rattle that makes the deck white as a snowfield in a second, and stings my face and bare arms, and crunches beneath my bare feet like broken glass.

‘Close the door!’ Izzy screams again and I fling myself against it as the wave breaks on us, a wall of water crashes down on the deck, and the ship shudders and staggers. Another wave rears above us and the door bursts open to admit a waist-high wall of water which pours in. The door is banging, Isabel is screaming, the ship is shuddering, struggling under the extra weight of water, the sailors are fighting for control of the sails, clinging to the spars, hanging like puppets with flailing legs, thinking of nothing but their own fragile lives, as the ship rears, the captain screaming commands and trying to hold the prow into the towering seas, while the wind veers against us, whipping up enemy waves that come towards us like a succession of glassy black mountains.

The ship reels and the door bangs open again, and Father comes in with a cascade of water, his sea cape streaming, his shoulders white with hail. He slams the door behind him, and steadies himself against the frame. ‘All right?’ he asks shortly, his eyes on Isabel.

Isabel is holding her belly. ‘I have a pain, I have a pain!’ she shouts. ‘Father! Get us into port!’

He looks at me. I shrug. ‘She always has pains,’ I say shortly. ‘The ship?’

‘We’ll run for the French shore,’ he says. ‘We’ll get in the shelter of the coast. Help her. Keep her warm. The fires are all out, but when they are lit again I’ll send you some mulled ale.’

The ship gives a huge heave and the two of us fall across the cabin. Isabel screams from the bunk. ‘Father!’

We struggle to our feet, clinging to the side of the cabin, hauling ourselves up on the side of the bunk. As I pull myself forwards I blink, thinking I must be blinded by the flashes of lightning outside the cabin window, because it looks as if Izzy’s sheets are black. I rub my eyes with my wet hands, tasting the salt of the waves on my knuckles and on my cheeks. Then I see her sheets are not black, I am not dazzled by the lightning. Her sheets are red. Her waters have broken.

‘The baby!’ she sobs.

‘I’ll send your mother,’ Father says hastily and plunges through the door, fastening it behind him. He disappears at once into the hail. Now and then the lightning shows the hail as a wall of white, smashing against us, and then it is black again. The black nothingness is worst.

I grab Isabel’s hands.

‘I have a pain,’ she says pitifully. ‘Annie, I have a pain. I do have a pain.’ Her face suddenly contorts and she clings to me, groaning. ‘I am not making a fuss. Annie, I am not trying to be important. I do have a pain, a terrible pain. Annie, I do have a pain.’

‘I think the baby is coming,’ I say.

‘Not yet! Not yet! It’s too early. It’s too early. It can’t come here! Not on a ship!’

Desperately I look towards the door. Surely my mother will come? Surely Margaret will not fail us, surely the ladies will come? It cannot be that Isabel and I are clinging to each other in a thunderstorm as she gives birth without anyone to help us.

‘I have a girdle,’ she says desperately. ‘A blessed girdle for help in childbirth.’

Our chests of things have all been loaded into the hold. There is nothing for Isabel in the cabin but a little box with a change of linen.

‘An icon, and some pilgrim badges,’ she continues. ‘In my carved box. I need them, Annie. Get them for me. They will protect me . . .’

Another pain takes her and she screams and grips my hands. The door behind me bursts open and a wash of water and a blast of hail comes in with my mother.

‘Lady Mother! Lady Mother!’

‘I can see,’ my mother says coldly. She turns to me. ‘Go to the galley and tell them they must get a fire lit, that we need hot water and then mulled ale. Tell them it is my command. And ask them for something for her to bite on, a wooden spoon if nothing else. And tell my women to bring all the linen we have.’

A great wave tosses the boat upwards and sends us staggering from one side of the cabin to the other. My mother grabs the edge of the bed. ‘Go,’ she says to me. ‘And get a man to hold you on the ship. Don’t get washed overboard.’

At the warning I find I dare not open the door to the storm and the heaving sea outside.

‘Go,’ my mother says sternly.

Helplessly, I nod and step out of the cabin. The deck is knee-deep in water, washing over the ship; as soon as it drains away another wave crashes on us, the prow climbs and then crashes, shuddering, as it falls into the sea. For sure, the ship cannot take this pounding for much longer, it must break up. A figure, shrouded in water, staggers past me. I grab his arm. ‘Take me to the ladies’ cabin and then the galley,’ I shriek against the shrieking of the wind.

‘God save us, God save us, we are lost!’ He pulls away from me.

‘You take me to the ladies’ cabin and then to the galley!’ I scream at him. ‘I command you. My mother commands you.’

‘This is a witch’s wind,’ he says horrifyingly. ‘It sprung up as soon as the women came on board. Women on board, one of them dying, they bring a witch’s wind.’ He pulls away from me and a sudden heave of the ship throws me onto the rail. I cling to it as a mighty wall of water stands before the stern and then washes down on us. It takes me, lifting me clear off my feet, only my hands snatching at the ropes and my gown caught on a cleat save me, but it takes him. I see his white face in the green water as it plucks him over the rail and he goes past me, turning over and over in the wave, his arms and legs flailing, his white mouth opening and closing like a cursing fish. He is out of sight in a moment, and the ship shudders under the hammer blow from the sea.

‘Man overboard!’ I shout. My voice is a little pipe against the pounding drums of the storm. I look round. The crew are lashed to their stations; nobody is going to help him. The water drains off the deck past my knees. I cling to the railing and look over the side, but he is gone into the darkness of the black waters. The sea has swallowed him up and left no trace. The ship wallows in the trough of the waves but there is another towering wave coming. A sudden crack of lightning shows me the door to the galley, and I tear my gown from the cleat that saved me and make a dash for the doors.

The fires have been washed out, the room is filled with smoke and steam, the pans are clashing on their hooks as they lurch one way and then the other, the cook is wedged behind his table. ‘You have to light the fire,’ I gasp. ‘And get us mulled ale, and hot water.’

He laughs in my face. ‘We’re going down!’ he says with mad humour. ‘We’re going down and you come in here wanting mulled ale!’

‘My sister is in labour! We have to have hot water!’

‘To do what?’ he demands of me, as if it is an entertainment of question and answer. ‘To save her, so that she can give birth to fishes’ meat? For without a doubt her baby will drown and her with it, and all of us with them.’

‘I command you to help me!’ I say through clenched teeth. ‘I, Anne Neville, the kingmaker’s daughter, command you!’

‘Ach, she’ll have to do without,’ he says, as if he has lost interest. As he speaks the boat yaws violently and the door bursts open. A wave of water sweeps down the stairs and breaks into the fireplace.

‘Give me some linen,’ I persist. ‘Rags. Anything. And a spoon for her to bite on.’

Bracing himself he reaches under the table and heaves out a basket of bleached cloths. ‘Wait,’ he says. From another box he brings a wooden spoon and from a cupboard he produces a dark glass bottle. ‘Brandy,’ he says. ‘You can give her that. Take some yourself, bonny maid, might as well drown merry.’

I take the basket in my arms and start up the steps. A heave of the ship throws me forwards and I am out in the storm, my arms full, and dashing to the cabin door before another wave breaks over the deck.

Inside the cabin my mother is bending over Isabel, who is moaning steadily. I fall inwards and bang the door shut behind me as my mother straightens up. ‘Is the galley fire out?’ she asks.

Mutely I nod. The ship heaves and rocks, and we stagger as it shudders. ‘Sit down,’ she says. ‘This is going to take a long time. It is going to be a long hard night.’

All through the night my only thought is that if we can plough through these seas, if we can survive this, then at the end of the voyage there is the outstretched arm of the Calais harbour wall and the shelter behind it. There is the familiar quayside where people will be looking for us, anxiously waiting with hot drinks and dry clothes, and when we come ashore they will gather us up, and rush us up to the castle, and Isabel will be put in our bedroom and the midwives will come, and she will be able to tie her holy girdle around her straining belly, and pin the pilgrim badges to her gown.