If I can do this, with children, their parents and even Ed King watching me, then maybe I can stand up and do my speech at the NASA competition. And if I can do my speech, then maybe Houston isn’t totally out of my reach …

‘So –’ Ed says, turning to me.

‘Come on!’ says George, pulling at his arm. ‘Don’t talk to her. I want to see the telescope.’

‘Go with Mum,’ Ed says, pushing him away. ‘I’ll be there in a bit.’

I start packing the rest of the fruit away while Grandad gathers up the toilet roll.

‘You’re keeping this?’ asks Ed, holding up the grapefruit.

‘If it’s not bashed,’ I say, not quite able to meet his eye. The science centre has paid for the props, but I don’t think they’ll mind if I take them home to make smoothies for me and Elsa.

For a few minutes, we pack up in silence. Even though I’ve been talking non-stop for an hour, I don’t know what to say now it’s just me and Ed. This is starting to feel like school.

‘Sorry about suddenly appearing like that.’ Ed breaks the silence. ‘George wanted me to volunteer and it’s easier to go along with what he wants. You didn’t look very pleased to see me.’

‘I was surprised. That’s all.’

He helps me arrange the watermelon so it doesn’t squash the other fruit. ‘Right at the start I didn’t realise it was you,’ he says. ‘At school, you’re so quiet and serious … plus you don’t wear a wig.’

I snatch the wig off my head – I’d actually forgotten I was wearing it. For a moment, I try to imagine being like that at school, just going to French on Monday morning and chatting to whoever is waiting outside the room, telling them what I did at the weekend … It just seems impossible.

Harriet seemed so much better at talking to people that I let her get on with it. She was a science geek like me, but she knew about other things too, about music, TV and clothes. She could talk to me about moon phases, then turn around and talk to someone else about Ed Sheeran, just like that … But it’s not just because I’m out of practice that I don’t talk. Honestly, I don’t think people want to hear what I’ve got to say. That’s why what I’ve just done has given me such a massive buzz. A buzz that I don’t want to go away.

I make myself look at Ed. ‘Maybe I should try to be less serious at school,’ I say. ‘Do you think I should roll toilet paper down the corridor and arrange fruit on it?’

He laughs. ‘Maybe.’

‘Do you want a grape?’ I hold out the bag to him.

‘OK,’ he says.

We stand there eating grapes until I realise that it’s my turn to speak. ‘So … Why did you come today?’

Ed shrugs. ‘It’s my brother’s birthday so Mum said I had to come as a treat for him …’ He trails off and stares into the corner of the tent. ‘Sorry,’ he says, ‘but I think someone’s left a baby behind. It’s playing with plums.’