On my command, the guns reload automatically, and we turn and fire a burst at the soldiers coming for us. This time our aim is better: the men go down, clutching their heads in pain.

Only in a dream could sponge darts be that effective!

The atmosphere in the crowd has changed in seconds. They watch in amazement as Seb and I run closer to the car, firing our toy guns at the uniformed officers, who have extracted their own pistols, but seem uncertain of how to proceed against two boys. One of them looks at Hitler as if for guidance, but Hitler continues to glare at us in silent astonishment.

This is even more fun than I had expected! I glance over to Seb: he has already downed the SS officer in a burst of orange missiles and is ready for another go at Hitler.

I raise my gun, tasking careful aim at Hitler’s moustache.

‘Okay, Adolf – get ready for one right in your gob!’ I shout.

My finger is squeezing the trigger when, from behind me, a large arm in a grey sleeve thumps down on the barrel of my gun, causing the ground in front of me to be peppered with orange foam. My assailant’s other arm grabs me in a chokehold and yanks the Nerf gun from my grasp, throwing it to one side.

I am caught, and immediately think about the Emergency Escape procedure. But before I can say anything I hear Seb scream from the other side of the huge motor.

‘Get off me!’

A huge soldier drags him, hand clamped over his mouth, his feet kicking up sand, until we are standing together facing the big black car, as Adolf Hitler climbs down and walks towards us slowly, his hands clasped behind his back, a cold half-smile on his damp lips. Following a pace behind is a stern-looking female SS officer, her cap pulled low, shielding her face. She is wearing the familiar black uniform, complete with the red-and-white armband featuring the hated Nazi symbol of the swastika.

She speaks first. ‘Silence! Ach so! Ve have a pair of Englishers, ja? In the uniform off the wunderbar Hitler Youth!’ She indicates me. ‘Do you see, mein Führer?’

Hitler nods solemnly, looking me up and down.

‘Ja, Kapitän Becker. Jawohl!’

This is good stuff. These people are talking exactly like the Nazi officers in Fit Billy’s film. For the full effect, the woman officer should click her heels together …

And she does. Then she takes off her cap, and angrily tosses her purple dip-dyed hair. I splutter with laughter when I realise she looks exactly like Kez Becker, and Hitler glares at me.