It was 1982, and he had been at the top of his game as a photojournalist for the best part of two decades traversing the world, capturing the horror of the world's wars with an unflinching eye.
You name it, he'd been there -- Cyprus, Congo, Vietnam, Cambodia, Bangladesh, El Salvador, Lebanon, Israel -- recording starving children, shell-shocked soldiers, mourning fathers, mothers with cholera.
Working for venerable British newspaper The Sunday Times throughout the 1960s and '70s, he'd won the status of a rock star for his battlefield bravery and amassed a catalog that, as he puts it, would "frighten most people to death."
Yet, the artistry of his compositions and the compassion with which he approached his subjects gave his work accessibility -- and for years it was his photographs that connected British people to the reality of wars and natural disasters in faraway places.
So when Britain went to war with Argentina over the Falkland Islands -- a windswept, remote chain in the South Atlantic -- it seemed only right to McCullin that he cover it.
But the British Army had other ideas, and he was not given an invitation to join the task force heading into battle.
"It was a crushing defeat for me not to go the Falklands War," he said. "In effect, I had more battleground experience than any soldier that went there."
Today, McCullin, a few weeks shy of his 80th birthday, describes what happened back then as "the beginning of tightening up against the press" by governments in conflict situations.
"The press had had pretty free rein in the Vietnam War ... to run around where we want, go anywhere, see anything," he said of the place where he produced some of his most celebrated work.
"But once the war was over, (there was a) feeling that it was the media that helped to lose (America) the war. We didn't."
It's not surprising the British government was wary of McCullin.
One of his great skills as a photojournalist was being able to shoot an image of something people find hard to look at and transform it into something they can't look away from.
"All the things I photographed would have been plain atrocity situations, but I had to create an image that would carry a message," he said. "I make it possible for you to look at them and try to come to terms with them instead of rejecting them."
He did it, he says, by being calm, dignified and allowing himself to think things through even though he was working in split seconds.
Right from the start he felt protected by his empathy. He describes it as wearing "a suit, not of armor, but a suit of compassion."
"Very early on, I started understanding what grief meant to people that were holding dead children or dead wives or husbands in front of me," he said. "I didn't have the God-given right to point cameras at them, but I used to search for their approval."
None of his achievement has come without a price: He's been shot in battle, but the deeper scars are psychological.
"I'm contaminated by darkness, by the fearful things I've seen," he said.
Around the same time he was rejected from the Falklands, he was fired from The Sunday Times for a joke he made about the paper, which misfired and hit the gossip pages.
"It was the beginning of me looking much deeper into myself," he said.
He started dabbling in landscape photography, shooting still lifes with fruit from his garden and oriental bronze objects, and self-funding trips to Africa and Indonesia to indulge his interest in anthropology.
He discovered an interest in archaeology, and these days he often gets his kicks photographing the cruelty of British scenery in the winter.
But, still, war finds McCullin -- even when he's not looking for it.
A few years back, he travelled around the Mediterranean taking photos of Roman ruins for a book called "Southern Frontiers."
They included the ruins at Palmyra in Syria, parts of which have been now destroyed by the terror group ISIS. While he was there, he sat down to tea with Palmyra's curator who was later beheaded.
And despite the years that have gone by since he was in the thick of it, he can't help but ask: "Why is it wherever I go or whatever I touch or see becomes a tragedy?"