Try as I might, I just can’t find the appetite for fish and chips because I have to get back to the bunker, without Grandpa Byron, and rescue Alan Shearer, and Grandpa Byron has noticed a change in my behaviour, I can just tell.

Still, time to put the plan into action. I pull my remaining glove from my pocket and pretend to look for the other one.

“I’ve lost my other glove,” I say. Then: “I think I know where. I think I dropped it outside our old house.”

“Don’t worry,” says Grandpa Byron. “We’ll go past on the way back and pick it up.”

But by then I’m halfway to the door.

“Don’t worry. It’s not far. I’ll go and get it,” and I’m out of the door while Grandpa Byron’s saying, “But Al – your fish and chips!”

It really isn’t far to our old house from the fish and chip shop – maybe half a mile, maybe less, but I sprint all the way, and I’m wheezing and lightheaded by the time I get there. So long as I can get there without being detected, and get down into the bunker, and grab Alan Shearer, I’ll be back in a few minutes – no sweat.

Fine. Yeah, fine. I take a deep breath, look up and down the street and cross the road and up the driveway of my old house, and as I slip though the broken garage door, I catch a glimpse of a silver Skoda coming round the corner and up the road.

No chance of moving slowly and silently now. Like I’m demented, I fling off the planks covering the steps. I’m turning the wheel that opens the steel bunker door as I hear the Skoda’s engine coming up the driveway, and the driver’s door opening.

I’m closing the steel door behind me when I hear the garage door scrape up and a muffled man’s voice mutter, “Bloody Nora!” Then, “Bella! Have you seen this? Have you been in here?”

Inside the bunker, I switch on the light. There’s no sign of Alan Shearer but I haven’t got time to look properly because the man’s footsteps are coming down the little stairway towards the bunker door.

“Oh my word, Graham!” says the lady I was talking to before. “Someone’s been here!”

I know what’s coming next, so I grab my side of the metal wheel that opens the steel door, and hold it as tight as I can when the man tries to turn it.

“It’s stuck,” he says, but gives another tug to try it. My arms are aching. “I need something to lever it open.”

His footsteps are retreating again, but I know I’ll be no match in strength when he comes back with something to force the door, and I can hear him poking around in the garage.

I’m trapped. I scan my eyes around the bunker, desperately looking for a hiding place. Under the bed? Too obvious. Behind the door? Not enough room.

There is one escape route, though.

Releasing the handle, I dash down the steps to the laptop and turn it on.

“Come on, come on!” I’m muttering at the screen as it goes through its start-up stuff. There’s a broom in the corner of the bunker, and I grab it and shove it through the spokes of the wheel-handle. It’ll buy me an extra few moments.

I can hear the guy coming back across the garage floor now. “This’ll shift it,” he says to his wife.

I’m in the tub and typing in the password now – The Lean Mean Green Machine – and waiting again for the program to load. When it does, I type in the letters copied from the top of the black box: WMAGGGGGWVE7G5E8GL2CWG

Then the time and coordinates like before, and I wait.

And nothing happens. I can hear Graham at the door, and he’s trying to get in and the time machine’s not working, and I’m hitting the ‘enter’ button again and again, but all that happens is … nothing.

I’m going to be caught.