‘This is good,’ says Granddad. ‘Now we walk up the other end of the lawn.’

I sigh and look at the mower on the path.

‘Granddad, can’t we just turn it on and push it like everyone else does?’ I point at the gardens around the square. ‘It’s just grass, Granddad, everyone has got it.’

‘Yes,’ says Granddad, ‘and look what a mess some of them make of it.’ He nods at the gardens where the grass has gone bare from people’s trampolines or from people parking their cars in front of their sitting room windows like Jake’s dad does.

‘But at least they don’t waste time measuring like we are,’ I say.

‘Preparation,’ says Granddad. ‘You should always prepare. Now follow me to the other end – you can hold onto the string as we walk.’

I follow Granddad with the string trailing out behind me. I’ve seen him mowing the lawn loads of times, but he seems happier and has twice as much energy today. I thought he just got the mower out of the shed, plugged it into the mains and pushed it. But he plans it like he does everything else. My dad says many Germans are meticulous and thorough. That’s why they’ve got straight autobahns and fast cars that don’t break down.

‘Okay.’ Granddad’s bending down with his tape measure again. ‘Now put the stick in the ground, pull the string tight and tie it to the stick.’

I do as he says and we both stand up.

‘There.’ Granddad wipes his hands on his overalls. ‘A perfect straight line. Now all we have to do is mow it.’

We walk back to the mower and Granddad puts it at the beginning of the line. ‘Remember we always start here,’ he says. ‘This is a1.’

‘What do you mean, a1?’

‘It will become clear,’ he says. ‘Now you push the mower, keep it tight against the string and I’ll hold the cable so we do not cut it by mistake.’

I put my hands on the mower’s handles and pull the yellow controller towards me. My hands start to vibrate as the blade turns. Granddad nods for me to start walking. I push the mower slowly across the grass, keeping the right edge close against the string, just like he said. It’s not as much fun as washing the car, but it’s way better than playing the glockenspiel.

I reach the end of the lawn where it stops by a rose bush. Granddad reaches across, taps my hand to let go of the throttle and takes over. I watch as he swivels the mower round then turns it off.

‘There.’ He smiles as he looks down the line I’ve just mown. ‘You have just mown your first file.’

‘You mean row,’ I say.

‘No,’ he says. ‘I mean file. And remember where you are?’

I look around me.