‘Actually,’ I say, ‘I think it would be better if we stay here on our own.’

‘Really?’ He sounds bemused.

The more I think about it, the more certain I become. With Mum gone, I’ve got the chance to get things sorted out a bit. Obviously I’ll have to keep Elsa here too, but she goes to bed at seven. Once she’s asleep, the flat will be mine. No Ibiza anthems, no community allotment meetings, no hot yoga (Mum really whacks the heating up for that), just peace and quiet … at a moderate temperature. I’d be able to work – I could practise my speech for hours. All of a sudden, Houston is back on the cards.

‘I can look after Elsa,’ I say firmly. ‘We’ll be fine.’

‘Well … I suppose it will make life easier with the chickens.’ He doesn’t sound that convinced, but I can tell he’s going to let me have my own way. Grandad hates arguments.

Elsa tugs at the phone, trying to get it out of my hands. ‘It’ll work out,’ I say firmly. ‘You’ll see. Before I go to school, I’ll drop Pongo round at yours and then I’ll take Elsa to nursery.’

‘Well … we’ll give it a go for a couple of days,’ says Grandad. Then his voice perks up. ‘Hey, I could make you both dinner when you come back from school!’

‘That would be great, Grandad,’ I say, trying not to think about the state of his fridge. ‘I’d better go. Elsa’s nodding off.’ She’s not. She’s very carefully trying to put her finger in my nose. ‘Goodnight!’

‘Goodnight, love. You girls get a good night’s sleep.’

I hang up the phone and look at Elsa. She stares right back at me with her round, blue eyes. A bit of confidence slips away from me. Elsa and I might live together, but essentially we’re strangers. Mum’s always trying to get me to hold Elsa and ‘bond’, but I haven’t got a clue what to do with her and it’s obvious she prefers being with Mum.

As if Elsa can sense my uncertainty, her face crumples and she starts to cry again. A ripple of panic sweeps through me and I wonder if I’ve just made a very stupid decision. I’m still holding the phone and as Elsa’s cries turn to screams, I’m tempted to ring Grandad back and say, ‘Move the hamster cages to one side. We’re coming round!’

I push the thought away. If I do that, I’ll never be able to enter the NASA competition. I’ve taken a computer apart and put it back together again; surely I can work out how to get Elsa to stop crying and go to sleep.

I decide to try shushing and patting. I’ve seen Mum do that loads of times.

‘Shhh,’ I say, and I give Elsa a pat on the shoulder. But this just makes her go rigid and arch away from me. Next, I try stroking her head, but she shakes it wildly from side to side. OK. I’ll try swaying. I start to sway my way around the flat, but if anything, this makes Elsa’s cries go up a notch. My heart beats faster and I decide to try it all at the same time: I sway, stroke her head, shush like mad and pat her back like it’s a drum.