‘Where are the other inhabitants of the house?’

‘My husband is away on a business trip. It’s my nanny’s day off, so she is out with her boyfriend. My mother-in-law is out shopping.’

‘As I explained when I entered the premises, I need to interview your children. Check that they are all right.’

‘Of course they’re all right,’ I reply as I lead her into the kitchen, where the boys are finishing off their pizza. Harry has cheese dribbling down his chin. I get a piece of kitchen roll and wipe his face.

‘Boys,’ I say, ‘this is Sonia. She wants to speak to you. Is that OK?’

‘Yes, Mummy,’ they say politely. ‘Are you a friend of Caprice’s?’ they ask.

‘Is Caprice your granny?’

‘Yes, but we’re not allowed to call her that.’

‘Why not?’

‘Because it makes her feel old, so she gets bad-tempered. She wants to be young again. If we call her Granny she glares at us with horrid eyes, and wags her finger. Her fingers are knobbly like a witch’s.’

Sonia turns to me, face like stone. ‘Please could you leave us. I need to speak to them alone.’

I tremble inside. Who is this woman? What is she doing here? What if she isn’t who she says she is? Or maybe it’s worse if she is. I step into the hallway and look her up on my iPhone. As soon as I type her name into Google, her photograph and job description appear. Sonia Watson. Exactly who she says she is. And she has an OBE for fund-raising for Childline. Panic rises inside me. Childline. Children who complain they are being abused. Why is she here, focusing on us? I stand by the door, ear pressed against it, straining to listen. But I cannot hear anything except the soft, whispering, background resonance of her voice. Of the children’s voices.

Every minute she is in there questioning my children feels like a year. When I finally see the door handle turning, I step back quickly and pretend to be rearranging the flowers in the hallway, like Caprice so often does.

Sonia Watson steps out of my kitchen, pushing her hair from her eyes, shaking her head and frowning. She doesn’t look happy.

‘Can I have a word in private?’ she asks.

I try to smile at her, but my lips don’t move. ‘Come into the drawing room,’ I suggest.

She follows me in and sits on the sofa. I sit on a chair by the fireplace bracing myself for what’s coming next.

‘I want you, or someone in the family, to take the boys to a GP for a thorough report on their medical condition. It’s Saturday today so the surgery will be closed. I’ll give you three days.’

‘But … why?’ I splutter. ‘What could possibly be wrong with them?’