Once I’ve got my legs moving and calmed my breathing down a bit, I come out of the cellar quickly, and close the heavy steel door behind me, spinning the wheels of the combination lock.

I’m still terrified of being caught, but my movements are smooth and quiet. I replace the planks over the stone stairway, and slip out of the garage, remembering to put the brick back in front of the double doors, then walk briskly among the shadows back to the moped. I get on it quickly, buzzing to the edge of town and back along the coast road, my head spinning with what I’ve just done.

The moon has moved across the sky and is higher and brighter than before. I am feeling really hot inside the helmet. On the outskirts of Blyth, level with the long stretch of beach, which is silvery grey in the moonlight, I stop the moped and take off the helmet for a moment, feeling a cool breeze through my sweaty hair.

Then I see the headlights of a car coming along the road. I turn my head to look, remembering too late that I shouldn’t be showing my young face and there’s another light above the headlights, on the car’s roof. The police car passes me as I put the helmet back on and start the bike again.

To be safe, I turn left at the roundabout, straight up a residential street that runs off the coast road and it’s just as well I do, because in my rear-view mirror I see the red brake lights of the police car come on and I see it turning around to come back. To follow me.

Desperately, I open the throttle of the moped as far as it can go, and the little engine whines in protest. I know I can’t go faster than a police patrol car, and as I look behind me, the car turns into the road I’m on and I hear the growl of its engine as the driver puts his foot on the accelerator.

In seconds the car is nearer, and his blue flashing lights are on – no siren yet, though. The road ends in houses arranged around the wide turning circle of a cul-de-sac. I’m trapped, and I’m going to have to brake soon anyway if I’m not to crash into one of the low front garden walls. Then I see it – a narrow footpath between the two end houses.

I mount the kerb with a rattling thud, which nearly knocks me off, hurtle towards the alleyway as the police car screeches to a halt behind me, and I hear the doors open and the beat of feet starting to run.

There is a metal bollard in the middle of the entrance to the alleyway and it’s going to be a tight squeeze, but I just manage it, scraping the side of the moped’s back end against the wall as I get past, and I know I’ve made it. I dare to look back and the two officers are running back to their car to try to get me on the next road.

I emerge from the footpath and I’m not even that sure where I’m going, so I turn right on the road in what I hope is the direction of Grandpa Byron’s street, although by now I’m panicking and my breath is coming in short bursts.

I turn left, just as I hear the police siren, and the car turns on to the main road in pursuit. They must have seen me. To my relief, I recognise the street: one more right turn and there is Baz’s corner shop and still the siren is getting closer. I have the throttle open fully as I get near to Grandpa Byron’s house and the engine is buzzing loudly in the night quiet and I completely forget about waking him up so scared am I that the police car will catch up.

I turn into Grandpa Byron’s driveway and kill the engine and lights immediately and push the bike up the side of the house.

Then the siren goes quiet.

This is almost the worst bit. I’m sitting on the ground, trembling and panting. The moped and me are pretty much hidden from the road when the police car creeps past at walking pace. I can see the officers’ heads turning from side to side and I shrink back further, hoping the wall will somehow swallow me up.

But then it passes and I breathe out. All the same, it’s a good twenty minutes before I can stand up and hurry back through the shadows to my house, and up the stairs and flop into bed.

And now I feel like I want to cry, but I stop myself, and instead take out of my pocket the letter that was taped under the desk.