I turn my attention back to the mammoth, which has cocked its leg on a rugby post and is peeing like a burst water pipe. Everyone is laughing.

There is something I want to try: something else that I recall from the instructions. I stand apart from my classmates, and, while they’re looking out of the window, I stand on my tiptoes and tell myself, Float, Malky, float! and I do, just a bit, as though a wire between my shoulder blades is lifting me up slowly. I start to laugh, even though, as I get higher, it’s a bit scary: if I fall suddenly, I’ll crash into my desk and chair and it’ll hurt.

Did I just do that? Am I floating?

The feeling makes me breathless with excitement. My mind is overflowing with thoughts. Did I really just control something in my dream? Am I really dreaming?

It doesn’t feel like it at all. It feels real – only I can float if I want to.

‘Oh, I say! Look at Malcolm Bell!’ goes a posh voice. I look down and it’s the girl in the blue jumper with the black hair from over the wall. She’s pointing and smiling her lips-together smile and everyone else is going, ‘Whoa!’ and, ‘Awesome!’ and, ‘Check out Malky Bell!’

By the time my head touches the rocky cave roof, I’m getting a bit freaked out, and so I say, ‘Down!’ but nothing happens. I push with my hand against the ceiling, and descend a bit, but then I bob up again, as though I’m a helium-filled balloon.

Seb grabs my shoe and pulls me down, but, as soon as he releases me, I float up again. This time I bang my head hard on the cave roof.

I don’t like this. ‘Down!’ I say again. ‘Let me down!’

This time, though, I really mean it. I am calm. I expect it to happen. And so it does. I flap my arms gently by my sides as I float back to stand on top of the school desk, and I do a little tap dance to make my classmates laugh. Mr Springham, the deputy head, has appeared and even he’s smiling.

Then there’s a scream (probably the Darcys), and people scuttle away from the desk, pointing underneath it. I watch from my position on top of the desk as the knobbled grey-green snout of a huge crocodile emerges, followed by the head and finally the whole fat body.

I look around: everyone has disappeared. It’s just me and a crocodile I have not seen in years.

‘You!’ I say, and it curls its scaly lip in response.

I swallow hard, wondering if it will still work. I hold out my hand towards the croc and, trying to stop my voice from quavering, I say, ‘Cu-Cuthbert.’