Remember: it was Seb’s idea. I can at least blame him for that. He was the one who came up with the idea of attacking Adolf Hitler.

It starts in Kobi’s cave. I’m getting a bit bored with the whole Kobi thing, to be honest, but at least I know it works and how to control it properly. It’s a bit like the early levels of a video game if you forget to save your progress: you can just whizz through to get to the bit you want.

Outside the cave are plenty of other boys the same age as me, all wearing the same uniform. I’d be sure to blend in, but I am still nervous.

There’s a crowd on the beach getting noisier. Beyond them, at the shoreline, are the mammoths that are usually there, but no one is bothered by them. I hear a couple of shouts go up:

‘Er is hier!’ and, ‘Er kommt!’ which I know from Miss Linton’s German lessons means ‘He is here!’ and ‘He is coming!’

I look down at myself and I don’t really like what I see. I am wearing a smartly ironed brown shirt and a neckerchief like the one I had in Cubs, only it’s black. My baggy shorts are held up by a shiny leather belt and on my head is what I now know is called a ‘forage cap’ because I looked it up on the web for my school project.

The uniform of the Hitler Youth.

The noise of the crowd has increased and more and more people are surging forward, but they are kept back by stern-looking policemen.

Then Seb turns up, dressed completely wrong. Instead of black, his neckerchief is bright green, made from the same fabric as his favourite goalie top. Still, no one seems to have noticed. I could get rid of him. He’d leave if I told him to. But I’m beginning to learn that it’s best not to be too controlling in these situations, if it can be avoided. It’s as if I’m allowed a certain amount of control, and it can get used up, like a battery.

I think of Mam’s song, and decide to just ‘let it be …’

‘Come on, Seb – head down. Got your weapon?’

‘Yep! Got yours?’

Do I? I look down – yep, there’s my Nerf gun. I pat the holster attached to my belt and unhook the cover in readiness. ‘Let’s go!’

We push through the dense crowd as purposefully as we can. No one looks at us.

I catch a glimpse of a car, still a hundred metres away, and to get a better view I say, ‘Float!’ and I begin to hover a little way above the heads of the crowd and nobody takes any notice at all. The car’s body is polished like a black mirror, coming slowly down the beach.

It’s the longest car I have ever seen: a Mercedes-Benz, open-topped so that everyone can see the occupants of the three rows of seats – although there is only one that anyone cares about.

In the back row are two grey-uniformed soldiers, staring warily at the crowd. In front of them, in the middle row, are two more officers. And riding up front next to the driver is the man everyone is cheering. He stands, unsmiling, throwing out his stiff-armed salute to the crowd, who return it, with grins and hoots of joy.

My heart thumps in my chest. He is so familiar to me from countless pictures, and YouTube clips, and movies and TV shows, and yet here he is in front of me, his car coming along the shore straight towards me and Seb.

‘Are you ready?’ I ask Seb again and he nods.

‘Ready, Freddie!’ he says.

The two of us step calmly from the front row and raise our blue plastic guns, ready to go down in history.

Malcolm and Sebastian Bell: the British boys who shot Adolf Hitler with Nerf guns.