In the days that followed our visit to Summertown, I found myself thinking about Anne Cleary a great deal. I’ve often wondered why people become murderers and I was shocked that I had met her years before, when she had been as ordinary as me, before she had allowed her son’s death to destroy her own life. I couldn’t get her out of my head: the ticking clock, the porcelain figures, the candles. She was gentler – and more genteel – than anyone I’d ever met. And yet, in Alderney, she had let loose a torrent of blood.

Was Hawthorne right to make the decision he had made?

He could have remained silent. Charles and Helen le Mesurier, two not very pleasant people, were dead and nothing was going to bring them back to life again. They were responsible for the suicide of Anne’s son and had probably harmed the lives of countless others – not that I’d thought twice before accepting an invitation to a literary festival sponsored by Spin-the-wheel.com. They had conspired to compromise Colin Matheson. A husband selling his wife, a wife cheerfully prostituting herself for her husband. They had blackmailed Colin and probably destroyed his marriage. They would have been happy to see war graves desecrated and an island torn apart – figuratively and literally – by a power line if it made money for them.

As far as the police were concerned, the case was closed. Derek Abbott, another unpleasant man, had been wrongly identified as the killer and he wasn’t going to complain about it any time soon. Anne Cleary was terminally ill. What exactly was there to be gained by dragging her daughter through the courts and putting her in jail?

Hawthorne had chosen to take the moral high ground, which was all very well, but I couldn’t forget the part he had played in all this. Although I hadn’t challenged him, I was almost certain that he had visited Derek Abbott and told him that the police had all the evidence they needed to make an arrest. Abbott had already spent six months in jail and he had told us that he would never go back. I remembered what he had said. He had used almost exactly the same words as he had written on his suicide note. I will never go back to prison. I don’t care what happens to me in my life, but I will never let that happen again. Had Hawthorne actually encouraged him to throw himself off the cliff at Gannet Rock? Whatever had passed between them, he had been complicit in the other man’s death and he was surely in no position to pass judgement on either Anne Cleary or her daughter.

And yet perhaps he was vindicated by what happened next.