The last time we met, well, let’s just say it was uniquely poignant. The Prime Minister, as I always thought of her, was attending Ronald Reagan’s funeral at the National Cathedral in Washington DC, carefully shielded by her daughter Carol, given her advanced dementia. Margaret Thatcher sat in the front row with the Reagan family, and those of us present watched her on a giant video screen, eulogising “my dear friend Ronnie,” as she called him. Incipient Alzheimer’s had persuaded her to record such tributes 18 months before.

Whatever some of us thought of her politics, you had to acknowledge the pathos. And the rapt attention shown by the great and good of the USA that day in the cathedral. You could sense attendees resisting the urge to stand up and applaud.

My boss, UN Secretary-General Kofi Annan, wanted to wish Mrs Thatcher well. He did so quietly outside as she left with Nancy Reagan, she being the only politician invited to travel with the family to the burial ground in California. Accompanying Mr Annan as the head of his Washington office, I had the chance to convey via Carol my best wishes to a woman I’d met decades before. “The Prime Minister and I go back to Finchley Grammar, circa 1969,” I said, glancing at Mrs Thatcher, catching her eye momentarily. Poor Carol looked understandably bemused. Her mother showed not a flicker of recognition.

As a longtime union member, I disagreed with her strongly, but kept my thoughts to myself

So back to 1969, and first acquaintance. A Friday morning in the sixth form interrupted by a message from the Headmaster’s office, telling me to join him downstairs for a surprise visitor. “Our MP is coming. She’s in the area seeing constituents and wants to stop by,” he told me as I hustled to join him. As head boy, it was my place to step out into the car park, and greet Margaret Thatcher as she drove herself in a rather battered-looking Ford Anglia. Simple headscarf, dark blue raincoat, and a small, brown handbag dangling over the arm as we led her into the main building, the underground trains of the Northern line in and out of nearby Woodside Park station drowning out greetings. But memory says the voice bore no resemblance to the accent we came to know years later. The voice training was yet to come.

Memorably, a small piece of ceiling plaster fell on a reading-desk as she toured the sixth form library. “That kind of thing makes such a mess,” she remarked, sitting down to talk to classmates. Asking about finances and resources, she insisted state schools like ours needed much more. “Schools like mine, schools like this, state schools, they are the engine of change.” Walking her back to her car, she asked me about my plans. “University, I hope. English Literature, my best subject,” I replied. “I dream of Oxford, but who knows?” She paused, opening the door, looking at me with the kind of serious intent that became her trademark years later. “Don’t just dream, young man, make it happen!”

In the years that followed, I saw her as a foreign correspondent, followed her journeys, spent days trailing her every move, interviewed her, but always abroad. So in Africa, the Middle East, the old Soviet Union, when she made one of her forays, well away from the turmoil of taking on the unions, downsizing government, or re-tooling Britain as a service economy. As a longtime union member, I disagreed with her strongly, but kept my thoughts to myself.

I loved the fact that, 21 years on from our first meeting, she still called me ‘young man’

I think of long, holiday weekends in the Middle East, when she made it her business to visit both sides of the Israeli-Arab conflict, listen, learn, and then use the microphone to champion the cause of negotiation, of peace. I recall Israel’s prime minister Shimon Peres, known euphemistically as a ladies’ man (how dated that seems) to us Jerusalem correspondents, clearly enamoured with Mrs Thatcher, leading to a cocktail party during her visit that oozed mutual admiration and warmth. But the following day she went to the West Bank, sat with Palestinian leaders, and digested their side of the story. On departure, she took both sides to task: “I tell you the time has come for the Israelis, and the Palestinians, to accept compromise, to reduce their territorial ambitions in the name of peace,” she told me before leaving Ben Gurion airport on a Whitsun bank holiday Monday, flying back to another round with Arthur Scargill and the miners.

Her husband Denis, who had sat beside me at her press conference at the King David hotel exclaiming loudly “hear, hear, Margaret,” took me to task for a sharp question about her political lovefest with Shimon Peres. “Denis, he’s just doing his job,” she said, touching her husband’s hand, as if to calm him down. “Let’s all have a drink.” We did, the three of us, and I reminded her of her visit to Finchley Catholic Grammar, and my dream fulfilled, of Oxford and English Lit at Lincoln college. “You see, I told you, make it happen,” she said.

In the same period, she visited Jordan, then Egypt, challenging the likes of Jordan’s King Hussein and Egypt’s Hosni Mubarak to turn quiet peace agreements with Israel into loud vehicles for breaking down barriers between Jews and Muslims, Israelis and Arabs. I followed Denis one morning in Cairo when he cut the ribbon on a giant sewage plant designed by British engineers. “I’ve just opened the largest shit-house in the world,” we heard him say on tape via our TV microphone. We never aired it or mentioned it. A different time.

And so to the final days of her tenure, when I was based in Moscow during the years of Mikhail Gorbachev’s Perestroika and Glasnost, her signature writ large on the process that led to the end of the Cold war. Just think about that ringing endorsement of hers early on about Gorbachev: “This is a man we can do business with,” she declared, brooking no naysayers, even though “dear Ronnie” had his doubts at various moments about the man’s commitment.

Even in Latin America you hear serious respect for La Thatcher’s no-nonsense, can-do leadership

When Gorbachev walked into a wall of opposition within the Communist Party ranks, she made a trip in 1990 designed to support him and to send his opponents the message that the West was no longer an enemy. Coming from the Iron Lady, her message echoed across the political divide in Moscow. “Can Gorbachev come through this?” I asked her, at the British Embassy as she prepared to fly home, this time to her own crisis within the Tory Party. “Mr Gorbachev will survive, I tell you,” she replied, giving me that beady eye oh so intently. “You look, sceptical, young man,” her voice now an octave higher, and tinged with anger. “I tell you again, Mr Gorbachev will survive!” Over and out. My editors at C4 News in London loved it. I loved the fact that, 21 years on from our first meeting, she still called me “young man”.

Mikhail Gorbachev did survive, for a while, but she didn’t. The Tory party removed her that same year. Gorbachev expressed astonishment when I saw him in the Kremlin shortly after her demise, calling her “a giant, dedicated to achieving change”. From Finchley Grammar, to Jerusalem, to Moscow, to Washington, never a dull moment with Margaret Thatcher — and never any doubt that she was there to make a difference, however much some of us disagreed with her policies.

She came to do — not just to be something — in her own caustic judgement of the politicians who followed her. “Don’t just dream, make it happen!”

Living these days in Latin America, I hear her called “La Thatcher”. And despite that triumphant victory in the Falklands war of 1982, or humiliating defeat seen from the other side, you hear as well serious respect hereabouts for La Thatcher’s no-nonsense, can-do leadership.