I’ve just got back from our first transfer, a casualty with a catastrophic haemorrhage. We took him to St George’s, rather than the Sussex, and now we’re back, the scene is more organized than when we first arrived.

Hundreds of people are here with one purpose – to preserve life. In the midst of all the pain, that thought gives me energy.

But then I see him. He has headphones on, like the ones we wear in the helicopter, but his are connected to a microphone, a ridiculously large thing covered in grey fake fur.

He’s following a woman with a camera who films a patient being extracted by a fire crew. She’s getting so close to him that it’s almost obscene.

I want to stomp over, to ask the two of them what the fuck they think they’re doing, getting in the way of rescues, filming people who are in no state to consent.

No. It’s a waste of energy, that’s not what I am here to do. I turn away and head back towards the second carriage. Carrot has to go back to base because his flying hours are so strictly controlled, but Lars and I are staying on. There’s no way either of us could leave.

The sounds are different now. Instead of moans and cries, the field hums with generators and engines and comms. It’s neither chaos nor order, but the systems are adapting to the scale of this particular catastrophe.

I find it harder to adapt to the magnitude of what I’ve had to do: I’ve never wanted to play God, but tonight I had no choice, picking my way between patients to find the ones who needed help first. Disregarding those that were past helping . . .

The Priority 1 and 2 casualties have all been transferred out, so Lars and I are going to meet in the area where they’re treating the walking wounded. The regional trauma centres are closed to everything but the most seriously injured, so helping people here in the field will mean fewer patients swamping the walk-in clinics. Plus, we need to keep an eye on these Priority 3s, to make sure they’ve been classified correctly and nothing more serious has been missed.

What was that?

The high-pitched cry is almost inaudible underneath the other noises. Did I imagine it?

It’s probably a farm animal: the bleat of a sheep whose territory has been invaded. After the things I’ve seen here, I wouldn’t be surprised if my hyper-vigilance is making me hear danger where there is none . . .

Except there it is again.

Is it human? A phone or music player discarded by a passenger?

I’m getting further from the train and from the floodlights that define the casualty area. I am about to turn back when I hear what I know is a voice.

‘Grandma? Mummy?’