The view from the Press Gallery

The nervous opposition leader gained confidence - and, as prime minister, turned into a deep-voiced

Her image seen from the Press Gallery had started softly. The early performance was tentative, nervous, formal. In opposition from 1975 to 1979, reports would agree (those of ardent Daily Telegraph-reading Tories included) that “Oh God, she was awful yesterday”. As leader of the opposition, she was regularly dismantled, reassembled and set gently down by James Callaghan, who was a triumph of avuncular manner over his sullen, vengeful self.

In government, during her early months before the 1981 Budget, Margaret Thatcher's style was modest, tentative. Contrast that with an interview in the late Eighties: "Yes, it will be difficult [significant pause] - but then I'm Maggie!" Yet, for the first 18 months, the senior liberal Tories, Francis Pym, James Prior and the outstanding Ian Gilmour, inhibited her.

They argued, warned, cajoled; she wilted. The television don Professor Bob McKenzie talked about men in suits who would come round and say: "Margaret, enough is enough." Then, at a bound (or a budget), she was free. The inhibitors were sacked, the men in suits reached for the garlic and crucifixes. And Bob McKenzie was struck dead a week later.

In the autumn of 1981, Norman Tebbit was hired to fix the unions. Professor Alan Walters proposed a budget that slashed a large number of billions from public spending; and, at a price of 3.5 million unemployed, everything fell into place. At a second bound - into the South Atlantic - she was not only free, but exultant. "We are a lion-hearted people."

We wondered if success would spoil Margaret Thatcher. It spoiled her rotten, and it spoiled her judgement (decisions such as the one on demutualisation went triumphantly through).

In fairness, the picture is more complex. She had her canny side, the boring-batsman-not-getting-out one. It appeared in the Commons on 28 November 1986, when Neil Kinnock asked if it was true that the attorney general had personally taken the decision to prosecute in the Spy Catcher case. "That," she said majestically, "was totally unworthy." Masterly Westminster pidgin for: "Don't expect a straight answer."

With people like Ian Gilmour, the real enemies on her own side, she stuck to formal court style. With a Labour member making himself vulnerable by being constructive, she knew the killer touch of a warm embrace. Witness Frank Field in a formal debate on welfare policy: I saw him caught betwixt flinch and blush when she told him that he was one person opposite whose opinion she really respected. Like being petted with a razor.

With the miners and the Argentinians done over and looking to a third term, Thatcher began to luxuriate. She talked too much. She went out into St James's Park to fight litter with a mini-shovel, a little bag and a verse promising that together we would "bag it and bin it". She became conceited, vain and - not easy for a woman - pompous. The accent, which Gordon Reece, as I heard in a famous pirate recording, had tried to guide away from ersatz posh ("No, Margaret, enuff, not enaff") regressed into regal. We were a grandmother.

She had a deep voice anyway, but was working it down to something very impressive, a sotto-contralto, distinctly Hammer Films. She began to resemble those six-foot lady-heavies who guarded nail-studded doors in sinister castles. She forsook civility for little bursts of escaped prejudice and perfect unreason. Neil Kinnock, heavily confined as Labour leader, required to wear smartly polished shoes and neo-regimental ties, was told in response to some innocent flutter of dissent that he was "a Marxist, a fellow-traveller". Similarly, in a BBC TV interview, she responded to a question about poverty and the consequences of her policies by telling the interviewer that she despised "drooling and drivelling".

How did the trade take to Thatcher's excesses? Gratefully. No journalist will ever object to excess. (Later, what did for John Major with the trade was his niceness.) The opposition was different. Denis Healey used metaphor. Margaret Thatcher, in his interventions, merged with Rambo, who metamorphosed into Rambona, or even Rhoda the Rhino. The backbenchers didn't do metaphor, but they hated her more. They often behaved like Thatcher's view of Labour, furious, indignant. She liked it, as it appealed to her anti-worker inclinations.

Essentially, however, Thatcher was losing it. She had been unkindly mocked in the early days: cruel jokes, bits of master-sex swagger from the rougher Labour benches and an element of snobbery from liberal Tories - "Ghastly middle-class woman!" (but then she was a ghastly middle-class woman). All these assaults had worked in her favour. It would be overdoing it to have expected the ten thousand swords leaping from their scabbards envisaged by Burke at the perils of Marie Antoinette. But sensible people winced, and a mild sympathy for her prevailed.

Not after a few years, though. In the Commons and on television, Thatcher had become a gold-plated steamroller, giving herself too many airs. Towards the end, she had got on so many nerves; and by then she didn't know how to get off them.

Edward Pearce worked in the Commons as parliamentary sketch-writer for the Daily Telegraph and the New Statesman between 1979 and 2002. His life of Pitt the Elder, "Man of War", will be published next year