‘Okay, he wouldn’t, but then I looked up the spies. There was a secret police in Germany, where your granddad comes from. They were called the Stasi and they went through people’s bins, looking for evidence that people were working against the police or the government. They got everywhere, bugged people’s phones and TVs, and they tortured people and put them in prison.’

‘What’s that got to do with my granddad? He’d never torture people.’

‘Maybe not, but didn’t you say he hates using the phone and rips up every single piece of paper?’

‘Yes, but . . .’

Jake kneels up. ‘Look, he’s going out. He’s been and got his hat and coat and now he’s locking his door. Come on!’

‘Where are you going?’

Jake grins back at me as he crawls across the platform. ‘To follow him of course!’

‘But he’ll only be going to the shop to get some bread or to meet his friends at the GFG.’

‘Then we’ll follow him there.’

Granddad puts his hat straight then closes his garden gate. Jake slides down the rope.

‘Come on,’ he whispers urgently. ‘We don’t want to lose him.’

‘Jake, this is ridiculous.’

‘So? It’s better than sitting up there all day.’

I laugh as I grab the rope. Jake’s taking this way too seriously, but I can’t stop myself from following him.

At the bottom we hide behind the tree and watch Granddad turn down the alley that leads out to the main road.

‘On the count of three.’ Jake holds up three fingers. ‘ONE, TWO, THREE!’

We scuttle across the grass like we’ve seen marines do in films.

When we reach the fence by the alley, we crouch down. Granddad is now at the other end, wearing his long grey coat. He looks left then right.

‘He’s looking for his accomplices,’ whispers Jake.

‘No, Jake,’ I say. ‘He really isn’t. I think he’s just crossing the road.’

A bus passes in front of Granddad. He looks left and right again, and then crosses to the other side. Me and Jake run down the alley. At the end we stop and crouch behind the green box that contains all the wires and fuses to the telephones on our estate. We peer over the top and see Granddad walking towards the row of shops.

Jake points to a white van parked outside them.

‘We’ll hide behind that,’ he whispers. ‘I’ll go first, you follow.’

Before I have chance to nod he’s already gone without even checking to see if the road was clear first. This is mad.

Jake reaches the white van. I look along the row of shops and spot Granddad going into the florist’s. The road is clear, so I run across and join Jake behind the van.

‘This is so cool,’ he grins.