‘You’ve got this part of it wrong, Mr Hawthorne,’ Anne replied, quite calmly. ‘Kathryn wasn’t with me on the Sunday. You’re right that I followed Mrs le Mesurier. I caught up with her before she reached the quarry and the railway line and we walked together, chatting quite normally. She mentioned the cave and I asked her to show it to me. It was a little out of her way, but I said I was nervous to go in on my own, so she took me to the entrance. That was where I hit her. I then carried her inside and finished the job inside.’

Was she telling the truth? I’m not sure that Anne Cleary would have been strong enough to carry Helen le Mesurier all the way down the dark passage that led into the rock face. But Hawthorne didn’t challenge her. ‘Did she deserve to die too?’ he asked.

‘She was just as guilty as him,’ Anne said. But I thought she sounded less sure.

‘She was an actress, playing a part.’

‘My son died. It destroyed my marriage. I have never had a moment’s peace since.’

‘They were horrible people,’ Kathryn agreed.

‘I don’t want you to say anything, Kitty! It’s very important that you understand that, now and moving forward.’ Her mother had drawn herself up in her seat. She knew exactly what she was going to say. Even as Hawthorne had been speaking, she had rehearsed it. ‘Could you please get the letter off the sideboard?’ she asked.

‘Mum . . .’

‘Please, dear.’

Kathryn wasn’t happy, but she got up and did as she was told. She handed her mother an envelope.

‘This may not make a great deal of difference to what you decide to do, Mr Hawthorne,’ Anne said. ‘For what it’s worth, I accept your conclusion. What I did was wrong and I expect to pay. Except that it seems I am paying already.’

She held out the letter. Hawthorne took it, a single typed page. I saw the NHS logo at the top.

‘You have heart disease,’ he said.

‘Left ventricular systolic dysfunction, to be precise,’ Anne told him. ‘I’m taking various medications . . . enzyme inhibitors and angiotensin receptor blockers. But my prognosis is not good. I have weeks, maybe months. It could just be days.’

I knew she was telling the truth. I remembered her breathlessness and the so-called antibiotics she had mentioned. On the morning after the murder, she’d said she had to leave the island for a doctor’s appointment and that was probably true.

‘This isn’t a payment,’ Hawthorne said.

‘I’m sorry?’

‘If you’re suggesting to me that you were sent this heart condition as a punishment for what you intended to do, that makes as much sense as Elizabeth Lovell and her stupid ghosts.’