The widow sits by the light of a spermaceti candle. What a profile she would make, with her aquiline nose and double chin! However, she is quick to cover it, flicking down her veil before standing and exchanging a formal curtsey with Agnes.

‘Miss Darken. How kind of you to call.’ Red cheeks burn beneath the netting of the veil; Mrs Boyle has evidently been crying.

‘Forgive my intrusion, I …’ Agnes gazes helplessly at the maid, whose eyes are pinned to the floor.

‘Leave us, Mary.’

Mary bobs a curtsey and trots away.

The forced darkness is unnerving. Mrs Boyle extends a black-gloved hand to gesture at a chair on the other side of the table, and for a moment she looks like one of Agnes’s full-length shades come to life.

Warily, Agnes perches on the edge of the seat. Her parcel fills her lap and she worries at the string with her fingers. ‘Thank you, Mrs Boyle. I shall not detain you for long. I simply heard what had happened and I …’ She wets her lips. What can she say? What can anyone say to atone for this? ‘I am so terribly sorry,’ she supplies feebly.

The widow sits opposite her with slow, heavy movements. ‘Thank you. You are in mourning yourself?’

Agnes glances down at her own black dress, momentarily bewildered. She has not worn a coloured garment in so long that she forgets how it must appear to others. But Mrs Boyle is unlikely to comprehend the general, lingering melancholy that causes her to prefer dark clothing. ‘A distant relation,’ she embellishes. ‘God rest them.’

The veil wafts as Mrs Boyle nods. She has certainly gone all out on her weeds – she must have emptied Corbould’s mourning establishment. Tassels, jet buttons, a ring already mounted with her husband’s grey hair. But then, who would not do the same? This is not simply a bereavement: the affliction of murder calls for shades deeper than a warehouse can supply.

‘I have not been receiving visitors,’ Mrs Boyle admits. ‘I have an abhorrence of their pity and their … questions.’ She places a hand on her chest, as if to put her emotions in order before continuing. ‘But I recognised your name. From the engagement diary. You … you saw him that day, didn’t you?’

The string pings from Agnes’s fingertips. She knows. Naturally, she knows. What a simpleton Agnes was not to think of it before. The policemen would hardly requisition the engagement diary without keeping Mrs Boyle abreast of their investigations.

Rather than answering, she pushes the package across the table.

Mrs Boyle unfolds the paper with painful exactness. This low candlelight is the perfect illumination for Agnes’s art. Little bronzed details glint – hair, a coat collar, the shell of an ear. Mrs Boyle draws in a breath.

‘There was to be a second appointment. A collection. Alas …’