Reunited with the Vietnamese 'girl in the picture'
When Chris last saw Kim, she was lying on a hospital bed with first-degree burns to more than half of her body, after a South Vietnamese napalm bomb attack.
It was 8 June 1972 and Chris and his crew had been in Vietnam for seven weeks, covering the conflict for ITN.
He remembers the day clearly: "That morning we'd arrived at the village of Trang Bang, which had been infiltrated by the North Vietnamese two days earlier. They were dug in, awaiting a counter-attack.
"In the late morning, two vintage Vietnamese bombers started to circle overhead - this wasn't anything unusual, but because we had been into the village we knew something was going wrong."
Many of the villagers had already fled to the shelter of a temple, among them nine-year-old Kim.
"We thought this would be a safe place - but then I saw the plane - it got so close," she remembers.
"I heard the noise of the bombs then suddenly I saw the fire everywhere around me.
"I was terrified and I ran out of the fire. I saw my brother and my cousin. We just kept running. My clothes were burnt off by the fire."
Chris and his crew were about 400m from the point where the four canisters of napalm had exploded.
"There was a blast of heat which felt like someone had opened the door of an oven. Then we saw Kim and the rest of the children. None of them were making any sound at all - until they saw the adults. Then they started to scream."
Lasting memory
A Vietnamese photographer, Nick Ut, was also covering events in South Vietnam that day.
As Kim ran down the road, her arms outstretched and screaming for help, he took what is now seen as one of the most memorable images of the Vietnam War.
She was still running when Chris stopped her and poured water over her, while directing his crew to record the terrible scenes.
"We were short of film and my cameraman, the late, great Alan Downes, was worried that I was asking him to waste precious film shooting horrific pictures which were too awful to use. My attitude was that we needed to show what it was like, and to their lasting credit, ITN ran the shots."
Nick took Kim to the nearest hospital, the US-run Saigon First Children's Hospital. Shortly afterwards, his photograph and the film footage appeared all over the Western media.
One result was that everyone wanted to know what had happened to the little girl.
It was Chris who found Kim the following Sunday, in a small room at the American hospital.
"I asked a nurse how she was and she said she would die tomorrow," he says. So he got her moved to a specialist plastic surgery hospital, for life-saving treatment.
Kim stayed in hospital for 14 months and went through 17 operations, remaining in constant pain to this day.
Her image became a lasting memory for a generation - but the little girl herself disappeared from public view.
Powerful gift
Then, 10 years later, a journalist from Germany tracked Kim down.
She was at university studying medicine but the Vietnamese government cut short her studies and ordered her back to her village to be filmed and interviewed. She was now a propaganda tool.
Even when she succeeded in resuming her studies, this time in Cuba, she was still expected to fulfil her duties as a "symbol of war".
It was at Havana University that she met Toan, a fellow student from Vietnam. They married and took a honeymoon in Russia, which provided them with a unique opportunity to flee to Canada.
"I heard rumours that a lot of Cuban students stay in Canada on the way back from Moscow, when the plane stops to refuel. By doing this I was finally able to gain my freedom."
Kim settled down to a peaceful and anonymous life in Canada with her husband and two children, but in 1995 she was traced by another journalist and the picture was splashed across the front page of the Toronto Sun.
"I wanted to escape the picture because the more famous it got, the more it cost me my private life. It seemed to me that my picture would not let me go," she says.
However, the realisation came to her she did not have to remain an unwilling victim. The photo was, in fact, a powerful gift that she could use to help promote peace.
"I realised that now that I have freedom and am in a free country, I can take control of that picture," she says.
'Impressive woman'
This idea led her to establish the Kim Phuc Foundation, which provides medical and psychological assistance to child victims of war.
Chris continued with ITN for another three years as defence correspondent, covering amongst other things the Yom Kippur War and the invasion of Cyprus. Later he moved to the BBC.
He retired in 1999 and never expected to see Kim again.
"At the time, it was just another story, though an appalling one. It was certainly the worst thing I ever saw.
"Later, when interest was rekindled, I felt that Kim was being used. That was why 10 years ago I declined a proposed on-screen reunion with her on the Oprah Winfrey Show - it sounded exploitative."
Now, having met Kim, he's changed his mind, and no longer thinks of her as a victim of that picture .
"Despite everything that has happened to her, and all she's endured, she's become a very impressive woman."