Geoffrey has finished lighting candles in lamps. He looks at Richard, who swallows.

‘All right,’ he says. Each bends to take one of Sir John’s heavy thighs and they haul them apart. She can hear the gasps of the men behind her. Between Sir John’s legs, just above the flopping sack of his testicles, is a dark wound the size of a thumbnail, weeping a pink-tinged, foul-smelling discharge. Buried under the powdery skin on his buttock, she can see a ribbed, slightly nubbled filament of scar tissue.

That must be the fistula.

Sir John moans.

‘Thomas,’ Katherine says. ‘Be ready with the sponge should he stir.’

Thomas climbs on to the bed from the other side, relieved not to have to watch.

‘Arderne recommends a clyster first,’ she says, talking mostly to herself. She takes the copper funnel from the dish of wine and holds it up. Under it hangs a dog-legged tube, as thick as a thumb, the end of which is punctured with numerous small holes. She fills it, lets the wine run out into the dish and then lets a thin line of the rose oil run over the funnel’s end before, taking it gently in both hands, she coaxes it into Sir John’s rectum.

He stiffens.

Thomas dips the sponge into the flask.

‘Wait,’ she says. ‘Not too much. Not yet. It can’t be good for him.’

Thomas nods.

‘Dafydd, pour the water in will you? Steady now.’

Dafydd steps forward and pours some from the ewer into the funnel. It gurgles down the tube.

‘Good,’ she says. ‘More.’

He pours more and water streams out on to the rushes below. She watches the dark head of the fistula bulge as if a worm were trying to escape the skin, and then the wound begins to weep a pale liquid. Small lumps of matter follow, and then uneven rivulets of bloody water dribble down his legs. When the flow slows she removes the copper and more water rushes from his anus.

Then she takes the probe. It is about eight inches long, beaded at both ends, made of fine malleable silver. She shakes the wine from it and then mutters a paternoster before she slowly screws one blunt end into the mouth of the fistula.

Again Sir John flinches and Katherine nods at Thomas. He wafts the sponge under Sir John’s nose.

Katherine guides the probe along the canal of the fistula, forcing the corrupt flesh before it, feeling the soft give of rotten tissue until it meets a different sort of resistance, spongy and unyielding.