‘It is more of a proxy than a precursor,’ Raven assured him. ‘Every blow I deliver to his door is one fewer I will be inclined to visit upon his person.’

Raven had insisted on accompanying the professor because Quinton’s ruthlessness in other matters meant he could not be sure what more the man might be capable of. He suspected Simpson had similar concerns, which was why he had acquiesced to Raven’s suggestion.

They both stood back and waited, listening out for footsteps within. Still no such sound was forthcoming.

Raven raised his arm a third time. A look from Simpson stayed his hand. Then Simpson simply opened the door, which was not locked, and led Raven inside, unbidden. This act of impolite transgression was in its own way a sign of a greater rage on the part of the professor than Raven had thus far displayed.

They proceeded down the long hall and into the drawing room, where they found Mrs Quinton seated by the fire. The baby was on this occasion asleep in a cot, one of only two items of furniture in the room. Flint’s big pay-day had evidently not yet arrived, or if it had, no dividend had been passed down. The place was still utterly denuded.

Mary Quinton got up in fright and alarm, standing with her arms folded.

‘Dr Simpson.’

The professor gazed towards the cradle. ‘Remarkable the bairn could sleep through all that hammering, is it not? Or perhaps the sound does not carry inside as I imagined it would, for surely your not hearing it could be the only explanation for why you would not respond.’

She stared guiltily at the floor.

‘Where is your husband, Mrs Quinton?’

Mrs Quinton resembled a startled field mouse, her eyes gazing involuntarily upwards, as though seeking intercession from the Almighty.

‘I do not know. He went out some time ago.’

‘And when do you expect he will return?’

Again, the look of being cornered and afraid. Raven recalled she was neither a practised nor adept liar.

‘I do not know.’

Once more her eyes flitted briefly up, this time towards the far corner of the room, where the door to the press was situated.

‘It is imperative that we speak to him,’ insisted Simpson.

‘He is not here,’ she repeated.

Raven had seen enough. He put a hand on the professor’s arm.

‘Let us away, Dr Simpson. I think I know where he might be. There is a place near Lady Lawson Wynd.’

Simpson gave him a sceptical look, which Raven answered with a subtle nod of assurance.

They exited forthwith, walking down the hall to the front door, which Raven opened and closed again heavily, though they remained within. Raven put a finger to his lips and bade Simpson remain quietly where he was. Then, a few moments later, they heard Mrs Quinton speak.

‘You can come out now, they’ve gone.’