I’ve just spent an hour in a Channel 4 News edit suite choked-up with Jon Snow and Margaret John, one of our finest video editors, writes Channel 4 News foreign affairs correspondent Jonathan Miller.

We sat in the darkness, glued to one of the most heart-breaking documentaries any of us has watched in a very long time. Twenty minutes in, Jon swings round in his chair, eyes brimming.

“Uhhh… wrenching,” he said. “Utterly wrenching. God, it’s a hard watch.”

But we couldn’t not.

Afterwards, we sat in shocked silence for a few moments.

“I can hardly speak,” Margaret said. “You just see it as it is. It’s so incredibly raw.”

“Walking Wounded: Return to the Frontline” is on Channel 4 tonight at 10.

I implore you: do not miss this film. If you do, watch it on 4oD.

It is a deeply moving story that delivers layer-upon-layer of insight into an almost unreported tragedy: the 55,000 — yes, 55,000! — Afghan amputees from landmines and ordnance left lying around in their country, now in its 33rd year of war.
What makes “Walking Wounded” particularly powerful, tragic and life -affirming in equal measure is that it is reported through the eyes of Giles Duley, a British photographer, who had both of his legs and an arm blown off exactly two years ago, while embedded with US troops in Afghanistan. Amazingly, the film opens with his medevac, shot on a soldier’s helmetcam. Even more amazingly, Giles Duley decided to go back.

This film is peppered with poignant still images he took with his one working hand on his return to the land of his nightmares.

He remembers the white flash, the intense heat, the terror. A week after he gets back to Kabul he is hit by flashbacks. “I am s******* myself,” he says. “Physically sick, because of where I am.”

But that doesn’t stop Giles Duley, a man who defied the odds by surviving at all. In the one hospital in Kabul dedicated to the care of Afghan amputees — run an Italian charity — he spends time with the recently wounded, joking with them, encouraging them, motivating them and taking their pictures. “Taking a photo,” he says, “is the only time I feel free.”

One of those he meets is Atawallah, an eight-year-old boy who lost his left leg and left arm when he stepped on an IED as he walked to school. They film him as his new prosthetic arm is fitted. Even Giles describes it as “heartbreaking” and talks about how everyone goes on about your legs, but it’s doing without your arm that’s the hardest.

“You can’t hug someone properly,” he says.

There are many memorable moments in this film, like when Giles walks into the Kabul prosthetics lab and is immediately surrounded by technicians who want to see how his £5,000 legs are built, with their hydraulic ankles. They ask his permission to disassemble his left leg.

Kabul’s leg-makers work with a budget of £150.

This is a film that has got to be seen — but it comes with an emotional health warning. I challenge you to watch this one dry-eyed.

Follow @millerC4 on Twitter.