Perhaps she had a point. I told her about how Gramps often talked about Steve at number eighteen, how he apparently dashes over the road every time his wife goes out, to the house where the bloke who always wears a skin-tight vest lives. And I told her about how he’s dismissed every single resident of Sefton Close, somehow deciding that they’re, ‘All into wife-swapping and dogging, every one of them.’ Sophia reckoned that one of the buildings on Sefton Road was, in fact, sheltered accommodation for the elderly and infirm, but we saw this as no reason to doubt Gramps’s theory.

‘Think about it, though,’ she said. ‘You can have nothing to your name, but you can still have better sex than a billionaire. Don’t you think that’s sort of wonderful?’

‘So that’s why the Sefton geriatrics are all throwing their mobility-scooter keys into a fruit bowl?’

‘Exactly.’ She slid down and stretched herself out across the sill, lying with her head resting in my lap. ‘I’ll be happy if I’m doing that at their age.’

It wasn’t talking about sex that did it. It wasn’t even the fact her head was resting in my crotch. It was the little black choker round her neck. It was just like the one the girl was wearing in that video I’d found a week ago and watched every night since. The guy grabs the girl by her choker, winds it round his fist, and uses it to ram her head back and forth. I felt suddenly furious that I’d viewed it so many times, furious that right now I couldn’t shake the image of it.

‘Are you prodding me, Ollie?’ she asked through a grin.

‘Sorry.’ An unexpected gulp caught me halfway through the word, breaking it in two.

She laughed quietly to herself. Heat flashed through my cheeks and out to the lobes of my ears.

‘Don’t be embarrassed,’ she said, tipping her head back and looking up at me.

I squirmed beneath her, intent on extricating myself, making my excuses and leaving. ‘I should probably be getting back,’ I said.

‘Don’t be stupid. Stay.’

I relaxed a little. Or at least most of me did.

‘I don’t want to go home yet,’ she said. ‘I want to be here.’

‘Same,’ I dared to whisper.

She lolled her head from side to side in my lap as she got comfortable again. Her eyes were focused nowhere in particular; her voice was soft and quiet. ‘It feels kinda big.’

‘So does size actually matter?’ I asked, my lips trembling.

‘Well, I haven’t seen that many, Ollie. Whatever you might have heard.’

‘Just wondered.’

She squinted up at me, making a show of considering the question. ‘Skinny ones are disappointing,’ she said.

‘Right.’