Martha composed her face into a smile, but in the moment before, he witnessed a glimmer of concern. It was as Sarah had observed: a fear of what she was permitted to say. However, as Martha warmed to the subject, it was clear that she remembered she did not need to fear being overheard.

‘We have our ups and downs, like all family I’m sure; blood relations or not. Sometimes we are like the oldest of friends, and other times I am grateful she has gone to live with her patients. Doubtless she is grateful to get away from me too. She once struck out on her own for a time after we had a falling out. She stayed in some squalid place, all she could afford. I convinced her to come back, but only by apologising. I can’t even remember what for, but it only mattered that it was me who admitted I was wrong. Mary never apologises. Mary is never wrong. I think it is because she had such a harsh childhood that she finds it hard to concede ground.’

‘Am I right in saying that this was not the house where you grew up?’

‘No. We lived at Canonmills: a much finer house than this. My father worked for the bank.’

‘Do you have other brothers and sisters?’

‘No. I was alone until my mother adopted Mary.’

Raven wondered at this way of putting it: that it was her mother who adopted Mary, not the family.

‘That must have been a disruption and a difficult adjustment, for all of you.’

Martha paused, considering her answer.

‘Like Mary, my mother was a strong-willed woman, and not to be defied. She saw it as her role to civilise Mary. To break her in, like one might do a horse. And it should be said, the instrument was the same.’

Raven had to conceal his reaction. The whip-hand indeed.

‘My mother succeeded, to some extent. She even changed the way Mary expressed herself, forbade her to speak as though she was from Glasgow. As you remarked the last time we spoke, she reverted and does so with all the greater pride now.

‘At the time I accepted much of this. I was oblivious and, I will admit, somewhat spoiled. I realise how hard it must have been for Mary, as I was the focus of so much more attention. It was my mother’s primary purpose in life to ensure that I married well, while Mary was shown no such consideration. She had already embarked upon a career as a nurse by the time I became engaged.’

Raven failed to mask his surprise.

‘You were married?’ he asked.

‘No. My husband-to-be died before we could be wed. His name was Colin, Colin Flett.’

She seemed to savour the sound of his name, a wistful look upon her face.