Having peered beyond a socket, I knew that even though nothing grew from the seeds, all sorts of other things go on inside walls. There are passages, and wires snaking from downstairs upwards, and from one room to another, a bit like veins. The wires are brown and blue, and they run between light switches, sockets and lamps, and they’re dangerous because you can pierce them with a drill. There are red and blue water pipes, too, and they can freeze even if they are red.

Apart from electrical wires, the sawdust walls contain old doorways and the ghosts of cupboards, and you can find out where they are by knocking. They’re a bit like the scars of the house. In the hall wall you can see where the house ended, once upon a time – now, the passage to the bathroom starts here. Upstairs, you can see a door-shaped panel – you used to get to a balcony that way. The wallpaper tears where the doorways are, because winter makes the chipboard sheets shift.

Once, Dad got red spots on his thighs and he thought we had brought back bedbugs from our holiday. He took all the mattresses, quilts, pillows and clothes into the sauna and turned the heat up. He sprayed large quantities of insect poison into the cracks in the bedroom walls and floor and smeared the bed legs with a thick layer of Vaseline. The mattresses baked in the sauna all that day and night, and groggy spiders crawled out of the walls, staggering along the wallpaper and dropping on to the bare bases of the beds. Mum was furious with Dad. No bedbugs were ever found.

MUM’S VOICE. When Mum’s fuming, her voice comes up from her tummy and her whole chest rings out. Once, she managed to prise fighting dogs off each other, she shouted so loud.

Mum coughs. That’s Mum’s voice when she’s on her own. Dad thinks Mum suffers from a dust allergy, but Mum doesn’t think so. Mum’s speech is soft and low, especially when she’s telling a story. Once, my friend got Mum on the phone and thought she was a man. Sometimes, Mum mumbles. That’s when she’s got pins in her mouth.

That’s what Mum’s voice is like.