Interviewed in these pages by Douglas Fraser yesterday, Wendy Alexander said something important and true. Quoting her colleague Charlie Gordon MSP, the new Scottish Labour leader asked: "How do we parent Thatcher's grandchildren - not just the sons and daughters of people whose life chances were stunted in the early 1980s, but the lasting legacy that scars our communities?"

Memories have faded a bit, I'll grant you. A generation of young adults possesses only a vague sense of a certain presence in Downing Street. For them, the divisions, the bitterness, the mass unemployment and social unrest are history. They cannot properly explain the baleful effects on their lives because they have no useful basis for comparison.

Alexander and Gordon make a good point, nevertheless. Thatcher-ism was more than the story of a decade. It leeches, still, through the generations. It is the paradigm, still, against which Westminster politics measures itself. "Lasting legacy" just about covers it.

Yet what was this, on the same day, on our front page? A remarkable photograph. A news event, no doubt engineered, but a news event. An image guaranteed to produce a precisely-calibrated effect on anyone 35 and older. Your reaction, more a conditioned reflex, would have explained a great deal about your life.

She's 81 now, and frail. The coiffeur is perfect, as always, but the fanatic light has faded from the eyes. The right arm is raised again, though - you can bet she waited until the photographers were ready - in that familiar near-salute. She is, as so often, accepting her due.

Thatcher. On the steps of No 10. With a child's bouquet in her hands. As a younger reader might ask: but wasn't she kicked out of power in a coup or something? Sort of, though it was funnier than that at the time.

I can certainly think of one friend of mine, a distinguished former industrial correspondent, who travelled all the way from London to Yorkshire just to celebrate the coup with "the lads" at the miners' welfare. I can remember the reactions, half-disbelieving, when the news agency snap came through. I don't remember any tears. Perhaps it was the company I kept. Perhaps it was just flint-hearted, vindictive Scotland.

None of that explains the reflex in 2007, almost two decades after Thatcher was ushered to the exit. Your queasiness - or possibly your warm appreciation - emanates from the other half of the image. Here's Thatcher and here, like her new best friend, is a Labour Prime Minister. With Gordon Brown in the frame, the timing of Ms Alexander's quote exhausts irony.

People change their minds. It would be a dull world if politicians did not mature and evolve. It's probably unfair, in fact, to cast the opinions of their younger selves back at them. Still, here goes.

Is that the Gordon Brown, lacking any sort of scrutable expression, who once published a book with a picture of Maggie on the cover? That was another famous photograph. It showed the then Prime Minister picking her way over an industrial desert. The book itself, published in 1989, was an excoriating attack on inequality, on the dismantling of manufacturing industry, and the destruction of hope. It's out of print. The chances of Mr Brown authorising a new edition from its Edinburgh publishers are, I suspect, slim. The title? Where There's Greed: Margaret Thatcher and the Betrayal of Britain's Future.

This is that future. In it, a Labour Prime Minister can be heard admiring Thatcher's convictions before he invites her for tea, a two-hour chat, and a photo-opportunity. In our present, the once-imagined future, the same Labour Prime Minister arrives from a frosty encounter with the trade unions to fete post-war trade unionism's greatest enemy. For good measure, Mr Brown's party has just hired Saatchi and Saatchi, the ad agency that once composed all of the devil's best tunes. None of these outcomes was predicted in Where There's Greed.

Yes, I know: it's all part of Gordon's cunning plan. He is adding another ridge pole to his big tent. He has invited Lady T for tea on the very day David Cameron has elected to publicise a Tory document designed to show off his cuddly green credentials. The Prime Minister is showing that he is above and beyond the sterile politics that leads young men to produce blistering socialist tracts. Judging by the comments on the ConservativeHome website, that refuge for dismayed Tories, the plan goes well.

Still, what was it Ms Alexander was saying about scars, legacies and stunted lives? More to the point, how does it square with the latest snap in the Brown scrapbook? Just to confuse matters, some of her recent remarks sound like notions from the Cameron camp. Those notions are, meanwhile, angering people who are supposed to support a certain David Cameron.

So has the Tory leader lurched leftwards from the far right, yet again? Was Brown's tete-a-tete with Thatcher a deliberate provocation to the unions, the party left and all those Labour voters who loathed the woman with a passion? Is Scottish Labour, new leader or otherwise, even on the same page?

I think I've just found the centre ground. It's over to your right. Far off to your right. That was Margaret Thatcher's real ambition, of course.

One of her offspring, in Ms Alexander's parlance, is standing next to the old lady in our photograph. The idea, from the beginning, was to shift the politics of Britain permanently to the right, to a position once regarded as lying on the fringes. The Blair-Brown years have been convincing proof of her success. The rich (or greedy) go on as before.

What's the worst that the latest Prime Minister has had to say about Thatcher over the past decade? I consulted his collected speeches in an effort to check. The worst - the very worst - Mr Brown has said is that Thatcherism was "too limited" in its view of "Britishness" and of Britain's place in the world. Her belief in "the need for change" is, meanwhile, heartily endorsed.

So when did that happen? At what point in the 1990s did Mr Brown step forward and say: "Hang on a minute, I've had second thoughts"? I can find no reference, just as I cannot trace the moment when David Cameron apologised for the intensely right-wing election manifesto he wrote for Michael Howard. Clearly, I don't get out and about on the centre ground enough.

To be fair, after that amiable tea in Downing Street, the Prime Minister's spokesman was keen to put the record straight. Of Mr Brown, he said: "He will never agree with what Lady Thatcher did on employment policy and other areas. But she was a strong leader who did much for Britain's image."

You have to love it. "Employment policy" - for four million people, it was known as unemployment policy. "Other areas" - areas, presumably, such as Scotland, Wales and the north of England.

Still, a strong leader with no image problems, unless the visceral hatred of millions counted as a difficulty for the folk at Saatchi.

I wish Wendy Alexander luck. Seriously. I just wonder if fixing the council tax, securing more powers for the Edinburgh parliament and repairing a sense of community is still the sort of behaviour that gets you invited to tea and the ever-drifting centre ground.