‘But have you yourself seen the crack?’ repeated Gunson.

Sheffield Harry nodded. ‘Aye, I ’av. It’s the narrowest hairline. Settlement. Nowt to worry about.’ He looked from Gunson to Craven and back, and grinned. ‘Wasted journey for thee, I’d say.’

‘Well, we’re here now,’ said Gunson.

‘And we won’t be relying on your say-so, Harry,’ said Craven. ‘Is Horsfield here?’

‘Nah, he went. An’ I’m off to. There’s a pint wi’ my name on it in the Barrel. Who’d be out on a night like this, eh?’

Sheffield Harry stamped past and disappeared into the night as quickly as if he had stepped behind a curtain.

Gunson wrapped his muffler more tightly about his neck. ‘We might as well have a look at it.’

They made for the valve house where a group of about a dozen men were huddled together. A figure broke away and trotted towards Gunson and Craven. It was Stephen Fountain, the father of the boy sent for Gunson.

Fountain wiped rain from his face. ‘Sorry to drag you out, gentlemen.’

‘Fill us in,’ said Craven.

‘No,’ said Gunson. ‘Sorry, gentlemen. Let’s see that crack first.’

‘This way.’ Fountain lifted his lantern to guide them. ‘Watch your footing. It’s treacherous.’

They had staggered up to within twelve feet of the crest of the embankment, by Gunson’s reckoning, when Fountain raised his hand to stop them. A gust of wind snuffed the flame in Fountain’s lantern as he lifted it towards the earth bank.

‘Damnation!’ he said. ‘This bloody weather.’

He clasped Gunson’s arm to guide him closer. Gunson attempted to adopt the same crouch Fountain was in, to get a better look, but his feet slipped from under him, and he went down on his knees, the cold and wet immediately penetrating his trousers. His face was now within inches of the earth bank, his nostrils filled with the smell of wet soil.

‘Look.’ Fountain took off his glove and Gunson watched as the man’s ghostly hand disappeared into the embankment. A magic trick.

Gunson frowned. ‘I was informed it was barely wide enough for a penknife.’

‘It was, at six o’clock,’ said Fountain. ‘It’s wider now.’

‘How long is it?’ asked Craven.

‘About fifty feet across,’ said Fountain.

‘Some settlement is to be expected,’ said Gunson.

He tested the edges of the crack with gloved fingers. ‘There’s no seepage. Yes, I’m sure it’s a small subsidence only. Have you checked the reservoir?’

‘Full to the brim. We opened the pipes, a while since an’ all,’ said Fountain.

Gunson nodded his approval. Reducing the pressure of water against the embankment would do no harm.

‘We had a job on, turning the screw. Took five of us,’ said Fountain.

‘Thank you. You took the correct measure,’ said Gunson. The opening of the sluice gate valves would release water into the river below at a rate of thirty thousand gallons a minute.

‘I should be able see the difference in the level of water from the inspection I made this afternoon,’ said Gunson. He clapped Fountain on the back. ‘You called me away from my warm fireplace on a wild night for this! No, no,’ he laughed to see the consternation on Fountain’s face. ‘I can understand your concern. You did the right thing. All will be well.’