She was the greatest Prime Minister since Winston Churchill, we say – and the comparison is apt, because she was as brave as Churchill; indeed, you could argue that she was even more combative than the wartime leader, more willing to pick a fight on a matter of principle.

First I remember the horror of the IRA hunger strikes, and my teenage disbelief that the government of this country would actually let people starve themselves to death. But I also remember thinking that there was a principle at stake – that peace-loving people should not give in to terrorists – and whatever you thought of Margaret Thatcher’s handling of the tragedy, you could not fault her for consistency.

Then I remember watching that Task Force head for the Falklands, when I was doing my A-levels, and thinking the whole thing looked mad. The islands were thousands of miles away and seemed to be mainly occupied by sheep. The Americans weren’t backing us with any particular enthusiasm, and the BBC was endlessly burbling on about some “Peruvian” peace plan, under which we would basically accede to the larceny of Argentina.

I could see that the Prime Minister’s position was desperate; and yet I could also see that she was right. She was sticking up for a principle – the self-determination of the Falkland Islanders; and I remember a sudden surge of admiration.

And when Arthur Scargill and the miners tried to unseat her in her second term, I remember the other students passing the bucket round in the Junior Common Room. I thought about it, since I could imagine that things were tough for communities where coal had been a way of life for generations. I could see how it would eat away at your self-esteem to be told that your labour was no longer necessary.

Then I reflected on what was really going on, and the way Scargill was holding a strike without a proper ballot, and the fundamental dishonesty of pretending that there was an economic future for coal. I suddenly got irritated with my right-on student colleagues, and was conscious that some kind of line had been crossed.

I was now a Thatcherite, in the sense that I believed she was right and the “Wets” were wrong; and I could see that there was no middle way. You either stuck by your principles or you didn’t. You either gave in to the hunger strikers, or you showed a grim and ultimately brutal resolve. You either accepted an Argentine victory or else you defeated Galtieri.

You either took on the miners or else you surrendered to Marxist agitators who wanted to bring down the elected government of the country. You either stuck by America, and allowed the stationing of missiles in Europe, or else you gave in to the blackmail of a sinister and tyrannical Soviet regime.

That was what was so electric about Margaret Thatcher, and that was why I found myself backing her in her last great battle, over Europe. Once again, it was a matter of principle.

The first time I found myself in her presence was at the Madrid EEC summit in 1989, which I reported on for this paper. I remember distinctly how she bustled into a packed and steaming press room – brushing right past me. “Phwof,” she said, or something like that, as if to express her general view of the Spanish arrangements.

It struck me then that she was much prettier than I had expected, in an English rose kind of way. I also thought she seemed in a bad mood. She was. As we were later to discover, she had just been ambushed by two very clever men – Nigel Lawson and Geoffrey Howe – and told that she must join some European currency project called the Exchange Rate Mechanism. She resisted, and they had threatened to resign.

She objected to their proposals, because she didn’t believe you could solve the country’s economic problems by trying to align sterling with other currencies in a kind of semi-straitjacket. “You can’t buck the market,” she said, and she was proved resoundingly right. The ERM turned out to be a disaster, and the British economy only started to recover when the pound crashed out on September 16 1992.

She was right not just about the ERM, but about the euro itself. She was virtually alone among all European leaders in having the guts to say publicly what many of them privately agreed – that it was courting disaster to try to jam different economies into a currency union, when there was no political union to take the strain.

Look at the unemployment rates in Greece and Spain, look at what is happening in Cyprus, and the sputtering growth of the eurozone. It is impossible to deny that she has been vindicated – and she was right because she took a stand on principle: that it was deeply anti-democratic to try to take crucial economic decisions without proper popular consent.

I cannot think of any other modern leader who has been so fierce in sticking up for her core beliefs, and that is why she speaks so powerfully to every politician in Britain today, and why we are all in her shade. In the end she was martyred by lesser men who were fearful for their seats.

But by the time she left office she had inspired millions of people – and especially women – that you could genuinely change things; that no matter where you came from you could kick down the door of the stuffy, male-dominated club and bring new ideas. She mobilised millions of people to take charge of their economic destiny, and unleashed confidence and a spirit of enterprise.

She changed this country’s view of itself, and exploded the myth of decline. She changed the Tory Party, she changed the Labour Party, and she transformed the country she led: not by compromise, but by an iron resolve.