Katherine takes the parchment from him. Over her shoulder he sees there are many illustrations, including one of an owl. A shadow of doubt crosses his mind. Whoever has drawn the bird has obviously never seen one in real life, and has drawn a duck with claws and a pointed beak. Elsewhere are pictures of plants that might be used in cures and a picture of a zodiac man, suggesting propitious times to cut into particular parts of the body, and a wounded man, too, showing the sorts of injuries that might occur in war.

‘I wonder if Fournier has seen this?’ Katherine asks. ‘When was it written?’

‘It says in the year of our Lord 1376.’

‘Nearly a hundred years ago. Even Fournier must have had time to hear of it, then. We should buy it. How much is it?’

The stationer names his price and without demur Thomas reaches for his purse. Katherine beats the man down to half. As Thomas pays the stationer, the old man hands her the parcel.

‘You bargain like a Jew,’ he says with a smile. ‘Or a woman.’

She says nothing, but takes the parcel and turns.

‘Thank you, Thomas,’ she says as they walk through the abbey yard.

Thomas is struck with an idea.

‘Perhaps, though, we might use it to start your lessons in reading?’ he asks.

‘Lessons in reading?’

‘Yes, why not?’

‘It would help pass the time, I suppose.’

So they sit against a wall, shoulder to shoulder, and he begins to coach her in the art of letters.

‘“A tretis extracte of Maistre Iohn Arden of fistula in ano,”’ he reads aloud, his finger following the line, ‘“and of fistula in other places of the body and of apostemes makyng fistules and of emoraides & tenasmon and of clisteres: of certayn oyntementes, poudres and oils.”’

They look at one another.

‘A difficult text to start with,’ he admits, ‘but it is what we have, so—’

By the end of the second week Katherine is beginning to read, with her finger under each letter of each word, but in the process she has acquired an intellectual grasp not only of the process of John Arderne’s operation for the removal or cure of fistulae, but also his various salves and ointments that make use of hedgerow plants such as hemlock and henbane, and his various theories about cleanliness in the surgery.

For all that time Sir John waits patiently, unsuccessfully, for an audience with the Duke, but it is as Katherine is finishing reading Arderne’s pages for the second time, beginning to enjoy his lively turn of phrase and his light-hearted boasting, that the lords finally reach their decision in the matter of the Duke of York and his claim to the throne of England, France and Ireland.