Baroness Thatcher: In her dreams, she is still prime minister

Margaret Thatcher may have been a lioness in winter, but she still knew how to roar. She did so last week by decrying Britain's EU membership and the echoes are still reverberating around the Tory party. Now the doctors have advised her to give up public speaking – a peculiarly cruel fate for a woman who lived through her voice.

It is a voice that will be missed by some and whose silence will be fêted by others. Her roaring arouses the same divergent reactions as her rule. To many Tories, especially in the provinces, she is still the voice of victory and of certainty: a heavy reminiscence of the days when their party found it easy to win elections, while Labour seemed finished. In other circles, one finds less enthusiasm.

She has become a liability for successive leaders of the Conservative Party, finding her way unerringly into the eye of the storm. Nor should this surprise anyone. Hers was never likely to be a benign old age. Margaret Thatcher herself used to nourish illusions about her retirement, before she had to endure it. Back in the late Eighties, when she assumed that she would be in No 10 several more years, she and Denis bought a large house in Dulwich. "So convenient for Waterloo,'' she would announce "I'll be able to pop off to town and have coffee with old friends in Peter Jones.''

But this desire to efface herself into the suburban upper middle class did not survive her loss of office, which was a profoundly destabilising experience. There had been no time for the psychological adjustments said to be necessary for a happy retirement – though even if there had been, it is unlikely that she would have made them. Resignation had never been one of her vices.

Nor was it after she had been compulsory resigned. As soon as she had left office, a new pattern of life was created around her. Dulwich was sold. Instead, there was a house in Chester Square, Belgravia, which instantly became a flat/ office complex reminiscent of 10 Downing Street, complete with policemen on duty near the front door and a large portrait of victorious Falklands warriors at the top of the staircase. There, the illusions of Parliament were maintained, as in other details. Throughout the world, ex-premier Thatcher could still rely on honours and deference. Her arrival quickened official pulses, and plenty of important visitors to London were delighted to receive invitations to pop round to Chester Square.

Equally, there were the memoirs, a massive – and lucrative – project, as demanding in time and energy as it was creative, in an opportunity to set straight the record: to justify the ways of Thatcherism to posterity. So there was plenty to do. Yet it was never enough, and for one basic reason. The new dispensation took Margaret Thatcher out of decision-making and into commentary before she was ready to renounce her frontline role. A Gulf war was imminent: a war which she had planned and inspired. Yet she had to watch from the touchline while others fought her war. It quickly became a matter of bitching from the touchline – and not only about the Gulf War.

As soon as she ceased to be Prime Minister Margaret, she lost the single most important asset she had preserved during her rule – she stopped being schizophrenic and allowed her purist idealism to win out. Confronted by the pragmatic sanction of reality, Prime Minister Thatcher always did a deal. But as soon as she ceased to be prime minister, she was not prepared to allow her successors the same latitude. Charles, now Lord, Powell, an unswerving Thatcher loyalist, is convinced she would have accepted more or less the same Maastricht Treaty as John Major did.

In office she was sustained by an extraordinary group of talented but unrealistic advisors. The most important member of the Thatcher government and exile is Robin Harris. Harris, who has a first and a DPhil from Oxford, was director of the Conservative research department during the 1980s; later on, he was a member of Mrs Thatcher's Downing Street policy unit. When she resigned as premier, he packed his briefcase and walked straight out of the building. There was no question that he would serve another. Harris, who wrote much of Mrs Thatcher's memoirs as well as rather a lot of the latest book on statecraft, is a man of high and formidable intelligence. But he is also a stern and unbending right-winger. He was able to accept the compromises of the Thatcher years, but only because he was dazzled by her force of personality. Once she ceased to be prime minister, he could not see any reason to allow her successors the compromises which he had indulged in her.

Harris is also a fanatical Catholic. Indeed, this once led to a public argument with Margaret Thatcher. Pressed on abortion during a meeting in the United States, Margaret Thatcher sought to deflect criticism by claiming that her relaxed position on abortion was the same as Harris's. Mr Harris interrupted her with indignant denials. His position was the same as that of the Holy Catholic Church's.

Another of her key aides has been Mark Worthington, who had dreams of the Thatcher Foundation becoming as internationally significant as the Adenauer Foundation, but that has not come to pass. What the foundation does remains mysterious. Speeches and books, not international good works, have been the Thatcher afterlife and she will miss the high profile – and the high revenue – from her speaking engagements. She has always enjoyed making money, although her personal lifestyle is modest. One recent visitor found her with Denis in the kitchen, the two of them dining on a soft-boiled egg and toast.

She retains her magnetism. Just before Christmas, there was a dinner in the House of Lords to celebrate Daphne Park's eightieth birthday. Lady Park, a senior figure in the secret services, had become a great friend. Lady Thatcher was the principal speaker, and arrived with prepared text. Throughout dinner, however, she hardly addressed a word to her right or to her left; she merely fiddled with the excellent speech as if she was overcome with nerves at the prospect of delivering it.

Since her recent stroke, she has slowed down and last week's stern warning from her doctors must surely reinforce that. Only a week before she had written a reply to an invitation to revisit the Falkland Islands claiming that she was in perfect health, but that Denis, 10 years older than her at 86, was too fragile for the trip and that she did not want to go without him.

This is still a woman who can produce much more adrenaline than she can consume. She has told friends that she still dreams about being prime minister, and then awakens to disappointment. She feels an overwhelming longing for the moral certainties of the Thatcher/Reagan era, when it was easy to slay dragons and win elections. As long as she is above ground, she will remain restless, defiant and unsatisfied. It is unlikely that she has ever been much of a fan of Dylan Thomas's. But there was one piece of advice that she never needed. Margaret Thatcher may be silenced. But she will never go gently into that good night.