I push open the doors, climb up and shuffle myself into position on the bed and pull the mask onto my face: it’s almost like it’s a part of me now. I’ve even decorated it to look a bit like Bear, after the play therapist said it’d make me feel better. And she was right. Every time I put it on, I think of his funny barks and his wagging tail.

My iPad is packed in the boot of Grandad’s car, so there’s no distracting music today and the noise of the giant gantry moving almost does my head in. I close my eyes, to shut it out . . .

Fern’s voice comes through the speaker. ‘All finished, Casey, my love. Well done!’

I glance back at the room before I leave it. Whatever happens, I’ll never be back here. This has either worked or it hasn’t: there will be no second round with the proton beam.

Mum’s waiting in the changing room and gives me a hug. ‘You’re so amazing,’ she says. ‘I’ll never understand how someone like me ever created someone as strong as you.’

Not just you, I want to say, Dad too.

‘Listen, Casey, before we go to wait for the consultant and the bell, I need to talk to you about something.’

She has her serious face on, and I don’t want to hear it. Have the doctors already warned her that Bob has grown?

Or is it Grandad? He wasn’t there at breakfast, and Mum said he’d gone for a mooch around the harbour, but he never does that, he’s all about being productive and focused.

‘I don’t want bad news. I can’t handle bad news today,’ I say. ‘Can you brush my hair for me, Mum? So I look right in the photos?’

She looks surprised, but we sit next to each other on the changing bench, and she uses the soft brush to tease the waves at the back of my head. She’s always been gentle, never pulling. It’s the first time she’s done it in so long; recently, I’ve not really had enough hair to brush through.

‘Are you going to keep the pink?’ she asks, like it’s a possibility.

‘I doubt Cheryl at Village Snips could do them like this.’

‘Well, we could go to a funkier salon in Cheltenham or Worcester. An organic one, obviously. You could even go on your own, on the bus.’

I turn to face her. ‘For real?’

‘You’re going to be a teenager soon. I swear you’ve grown up by about a year in a single month.’

‘They won’t let me have pink hair when I go back to school.’

‘You’d get away with it, after what you’ve had to go through. I could send a note, say the pink is a side effect of the proton beams.’ Mum giggles.

I laugh too. ‘I’m hoping no one at my new school will know about Bob. I don’t want to be tumour girl. I want to be normal.’