I can deal with my grandmother by rote. I have heard her graveyard instructions so many times they no longer shock me. By my mid-teens, I got to the point where I could parody them for Milly, and have her laughing so hysterically she would beg me to stop before she wet herself. The silver lining – and it is a vital one – is that Zac found my grandmother so horrible he was never around her enough to hear these instructions too. He met her once, and that was enough.

‘Yes,’ I say. ‘I know he was a hero. I’ll be sure to keep him in the middle.’

‘In the family vault.’

‘Yes, I know, Grandma.’

‘The graveyard’s closed to new burials, you know, but not to us.’

‘We’re so lucky. We know so many of the dead.’

‘It wouldn’t have happened, you know. He’d still be alive. They’d both be alive if your mother hadn’t pushed and pushed for them to go that day. She made friends with some other RAF wife, you know – got them invited to that lunch party. Your father didn’t want to go. He hated that sort of thing . . .’

‘What’s so wrong with her making a friend and who was the friend and why didn’t my father want to go?’ How many times in my life have I asked these questions? But my grandmother merely shakes her head and makes a motion of sealing her lips.

Time and again during my childhood, I searched the house for clues and found nothing. I set up a recorder by the one landline my grandmother had, and monitored her conversations. All I discovered was a litany of complaints about the woes of raising a child in old age, gossip about geriatric infidelity, blackmailing threats to leave her electricity and gas provider for a better deal, and her endless pestering of saintly, patient James about her many prescriptions.

She is beyond any ability to answer these questions now. ‘Never mind.’ I kiss my grandmother’s papery cheek. I put a box on her lap. She attempts to peel off the plastic but gets nowhere, so I do it for her, then lift the lid. ‘Peppermint chocolates. Your favourite soft ones. No hard centres, so you won’t struggle with your teeth.’

She puts one in her mouth and starts to chew. Zac said that watching her eat had put him off his food for several days – that was probably the thing that helped most to keep him away from her. And the fact that he said she was a cross between a dragon and Cruella de Vil. I take out a tissue to wipe her lips and chin, but she bats away my wrist.

She uses her special whisper for what she says next. It is a whisper so loud I imagine the dolphins can hear. ‘You are evil,’ she whispers. ‘Just like your mother.’

‘Please, Grandma—’