Bertie acknowledged the compliment. ‘Thank you,’ he said. ‘Italian is very easy. I could teach you, if you like.’

‘That’s a good idea,’ said Andy. ‘I could learn Italian and we could make a fort.’

He extracted another penknife from the drawer beside his bed. ‘And this one here is a really good Swiss Army penknife,’ he said. ‘The Swiss Army is famous for only fighting with penknives. They don’t use guns, you know.’

‘I’ve heard that,’ said Bertie.

‘And here’s another Swiss Army penknife,’ Andy continued. ‘It’s a bit smaller, but it’s still really useful. This blade here is for cutting bits of wood. And you see here? That’s a set of scissors.’ He paused. ‘Would you like it, Bertie? You can have it, if you like. I’ve got that bigger one – you can have this one.’

Bertie’s heart gave a leap. ‘Are you sure?’

‘Yes. I want you to have it. You’re my friend, you see. So I want you to have it.’

Bertie took the knife from Andy. ‘Thank you,’ he said. ‘You’re my best friend now, you know. My very best friend.’

Andy nodded. ‘Same here.’

They shook hands. It was a solemn gesture, cementing the new friendship, and it seemed to Bertie then that his entire life had changed. He slipped the penknife into his pocket, relishing the smooth feel of its casing and its solid, reassuring weight. He was about to say something more, to thank Andy again for the gift, when they heard Andy’s mother calling from down below.

‘That’s my mum,’ said Andy. ‘She’s calling us.’

They went downstairs. The farmer’s wife had laid two cups on the kitchen table, alongside a plate of scones. Two glasses stood beside the cups and at their side was a large bottle of orange-coloured liquid.

‘Oh, good,’ said Andy. ‘Irn-Bru, Bertie.’

Bertie was puzzled. ‘Iron what?’

Andy looked at him in astonishment. ‘Don’t you know what Irn-Bru is?’

Bertie shook his head. ‘We don’t have things like that,’ he said.

‘Irn-Bru is really good for you,’ said Andy, reaching for the bottle. ‘I’ll pour you a glass. You’ll see.’

Bertie looked at his father. Stuart smiled. ‘Try it, Bertie. I think you’ll like it.’

Andy poured a glass of the fizzy orange liquid and passed it to Bertie. ‘It’s made of girders, Bertie. It makes you really strong.’

Bertie took a sip, swallowing tentatively and then gulping the drink down. He had never tasted anything like this before, and he loved it. Andy filled his glass again. ‘You can burp if you like, Bertie. You’re allowed to burp when you drink Irn-Bru.’

Bertie burped.

‘That’s good,’ said Andy, finishing his glass, and then burping too.