Tony Blair met me in the cabinet room and ushered me through the french windows into the garden of No 10. “It’ll be quieter here,” he said.

The prime minister had agreed to see me to talk about Margaret Thatcher. What surprised me was the extent to which he was prepared to acknowledge her strengths, and to make it clear that he wanted to emulate her.

“She was a very fine intellect,” he told me, speaking as one former lawyer about another. “She had a really uncluttered mind, a very clear mind . . . a clear way of expressing herself.”

I should admit that at the time of our interview he was still enjoying one of the longest political honeymoons in British political history. It was the summer of 2002, and the war in Iraq lay in the future. But there was still plenty to concern him; he was worried about the need to give his period in office a sense of direction, about how his narrative might appear to future historians.

As a politician, what Blair most admires is the way that Thatcher set a course for her party in government which radically changed the history of Britain. He was particularly impressed by her “tremendous clarity of objective, matched by huge determination and vigour”. Compromises along the way were acceptable, but “she never yielded her ultimate goal”.

He went on: “She was a considerable prime minister. It is foolish for anyone, left or right, to deny that. She understood the importance of putting trade unions into a proper legal framework. And she understood the need to take an axe to some of the things in the public sector that were out of date.”

He believed that, had she not been overthrown in 1990 by Tory MPs fearful that her unpopularity threatened their seats, she would have recovered and won a record fourth general election victory against Labour.

Blair revealed that he had talked to her “reasonably regularly” since becoming prime minister, and they particularly kept in touch over international issues.

“I found her immensely helpful over Kosovo,” he said. “She was very kind personally. She understood the pressure. She was very good about advising me on how to take the military advice on board, and how to use it.”

She had told him to trust his instinct when things got rocky. He smiled as he recalled what she had said: “You are doing the right thing; don’t pay any attention to the critics. Go on and get it done.”

Now compare Blair’s tribute with what some of Thatcher’s own former cabinet ministers and aides say about the way she meddled in Tory affairs in the years after she was overthrown. I’m not going to revisit all the gruesome details of her complaining and interfering — ERM, Maastricht, the euro, the Tory leadership and the rest — but these public comments by those who had to put up with her are unprecedented.

Douglas Hurd, now Lord Hurd, told me: “Most of us have a brake which operates between what we think and what we say; but that brake wears out, and it wore out with her. So she was saying things that were on her mind, but there was no sort of sieve or filter.”

I was just finishing my interview with Hurd in the tearoom of the House of Lords when I came across another former foreign secretary and Conservative grandee, Lord Carrington.