Edward went on in that flat, toneless voice. ‘Always Isabel and I kept a mask of loving childishness before him, and he did not see through it. We used to giggle at his innocence. And then Isabel had the idea of killing him. To secure that inheritance, and gain vengeance. For depriving us – as we had persuaded ourselves – of our inheritance.’ He closed his eyes. ‘And for not being our dear father, whose place no man could take.’ A tear coursed down Edward’s lined cheek. In that house, I thought, there was no reminder of their real father save that wall painting, no one left whom they trusted, whom they could talk to. Some children make friends among the servants, but I guessed neither Edward nor Isabel had been that sort of child. They had driven each other slowly but steadily into a kind of madness.

Edward continued, ‘We talked of all sorts of plans to kill him secretly, but could not think of one that might work. I truly believe I never intended to match the word to the deed, though perhaps Isabel did. Then that day on the wharf – Peter Cotterstoke looking out over the river, right on the edge of the wharf; Isabel whispering in my ear that now was our chance. The tide was full and the water cold, he would not be able to climb out. It took only one push from behind, and I was a big boy, tall for my age.’ He lowered his head. ‘Strange, it was only afterwards that we realized what we had done. Murder. Isabel took charge, decided we must say we had left our stepfather at the wharf.’

Philip said, ‘And no one could prove otherwise.’

‘And then – then we learned he had not planned to disinherit us at all.’ Edward hid his face in his hands, his voice scarcely audible. ‘Mother suspected, somehow. Afterwards she could not stand the sight of us, got both of us out of the house as soon as she could. She had no interest in my family, her grandchildren. And that Will she made – ’ He broke off.

I said, ‘Her revenge.’

He shook his head. ‘Yes. I see it now. I never thought Vowell had guessed, even on the day of the inspection when he was so upset. I have been blind, blind for so long.’ He made a fist of his hand and banged it against his forehead.

I said quietly, ‘All these years, you and Isabel have blamed each other, because it was easier than facing the truth.’

Edward nodded dumbly. ‘A truth too terrible to bear.’

‘In a way all this time, you have still been conspiring together, each determined to avoid your share of the blame.’ It was a strange, turnabout thought.