One of Margaret Thatcher's celebrated recent invocations was, at the time, accounted the most disgraceful. It happened in June 2006 when the BBC presenter, Jonathan Ross, asked the new Conservative leader David Cameron whether, as a youth, he had used images of the iron lady as a means of non-ideological stimulation. Many people felt that this was not only a crude impertinence (which it was), but also that Ross was introducing extraneous emotion into an essentially intellectual area.

But, as anyone who watches Michael Portillo's new BBC Four programme The Lady's Not for Spurning on Monday, will soon realise, Ross was on to something. For what Portillo reveals is that many Tories, especially male Tories, were indeed deeply in love with Mrs Thatcher, and could not bear what was done to her - or what they had helped do to her - in the autumn of 1990. The Conservative Party itself, says Portillo, became - and may still be - the victim of their feelings of hatred and guilt.

“We thought she was brilliant,” says Portillo, early in the piece. “I entered politics because she had inspired me.” Being near her was “exhilarating,” he goes on, and many like him felt “captivated”. Readers hardly need me to point out that “captivated” is a magical love word, to be used alongside or instead of “beguiled” or “enchanted”. So when it was time - just before the second ballot for the Conservative Party leadership in 1990 - to tell this captivating woman that she was about to lose to Michael Heseltine, it became, for Norman Lamont, “one of the most awful moments in my life”, and for Michael Howard, “the most emotional discussion that I have ever taken part in.” “I was gutted,” says ultra-Thatcherite MP Gerald Howarth. “I have never seen so many grown men with tears in their eyes.” And then Howarth tells Portillo, in language he may not have used about his own wife, “I am, I was and I will be, utterly devoted to her.”

So well does Portillo create the image of the youthful, handsome Oxbridge student's infatuation with something new and blue, that when, in his words, “little clouds of doubt began to appear in our Thatcherite sky,” and the music turns anxious, one is reminded of nothing so much as the TV adaptation of Brideshead Revisited. Charles Ryder starts to understand that Sebastian is a drunk, Lady Marchmain is a monster and the house itself is full of unhappiness; Michael Portillo senses that the poll tax may be disastrous and that Margaret treats some of her most important colleagues with a dangerous contempt, but love prevents action.

Of course, not all of this is easy for the non-Thatcherite to grasp. The Thatcherites' instinct was that if you weren't with them, you were against them, as David Mellor recalls. If you weren't in her camp - or if you were in any way opposed to her - if you thought Mandela was the hero and Pinochet the villain, rather than the other way round, then the experience was one of repulsion rather than attraction. Many of us can only be forced to allow that many of Thatcher's reforms may have been necessary through the most painfully gritted of teeth.

What, in the end, made it all so historically tolerable was the way in which Thatcher's character, and the love that her followers had for her, helped to destroy the intolerant, strident, illiberal Conservative Party, as she had also helped destroy our socialism. As Portillo suggests, the bitterness - both hers and her supporters - at her demise, divided Major's premiership, derailed Hague's leadership, promoted the disaster of Iain Duncan-Smith's election, inhibited Michael Howard's caretakership and, even today, haunts David Cameron. It would have been better, Chris Patten tells Portillo, in a quite remarkable change of mind, if she had been allowed to stay on and lose the 1992 election. The poison, he believes, would have been drained. Instead, says Portillo, “blinded by nostalgia”, the Conservative Party became an entity with its “eyes off the future, hypnotised by its past.”

Though Tony Blair (like Gordon Brown) admired Thatcher's toughness, his over-riding objective, when he considered his own departure, was that it should not be attended by the dreadful legacy of division she left behind. So determined was he to avoid stories about his attitude towards his successor, that he refused even to watch news reports of the formation of Brown's first cabinet, lest his body language be said to reveal something of his inner thoughts. No one has managed to pin a single critical quotation on Blair, about Brown or about any policy, since he departed in July last year. Such was certainly not Lady Thatcher's way. Her icy undermining of John Major and her sponsorship of Hague and Duncan-Smith spoke to a determination to live on after death. Her occasional emanations, as when - alongside Howarth and Lamont - she campaigned for former dictator Pinochet not to be extradited to Spain, were spectacularly unlikely to help change the image of her party.

Only now, 18 years after her departure, does the shadow seem to have lifted a little. If Cameron can somehow park the issue of Europe, then he will have transformed the outlook and profile of his party. But, of course, political life is rarely so straightforward, for it is precisely at this time that television and the movies seem to have decided that Thatcher is safe enough to be historicised and re-imagined - not as the divisive old bat of the last two decades, but as the conviction-Boadicea of our older erotic memories.

The BBC is said to be involved in two Thatcher dramas, The Long Walk to Finchley, about her gutsy fight against a male-dominated establishment to become an MP at the beginning of her career, and Margaret, about her gutsy fight against a male-dominated establishment to become leader and then stay on as PM at the end of her career. And then there is the Pathe drama-documentary on how gutsy Mrs Thatcher took on the Argentinians and won the Falklands war.

Mr Cameron must be hoping that all this Maggifying will see the creation of a Mrs Thatcher the historical figure, and not the reburnishing of Margaret, the Tory love object.

Portillo on Thatcher: The Lady's Not for Spurning, Mon, BBC Four, 9pm

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