If the Falklands war was the watershed event of the first Thatcher government, that of the second Thatcher government was the successful conclusion of the year-long miners' strike. Here again myths have grown up, not least that Margaret Thatcher came into office with the undeclared but implacable aim of smashing the National Union of Mineworkers (NUM). Nothing could be further from the truth. When she appointed me Energy Secretary in 1981, the only instruction she gave me was, "Nigel, we mustn't have a coal strike" - and she meant it. Like the rest of the Heath government, she had been deeply scarred by the half-truth that it had been brought down by the NUM and she did not wish that to happen to her.

However, when the militant Marxist Arthur Scargill was elected NUM president a few months later, that is precisely what he intended to try to do, touring all the mining areas of the country seeking support for a strike. It was clear to me that, unless we were to surrender to his inordinate demands (which were, of course, intended to be unacceptable), a strike was sadly inevitable and the only practical course was to prepare for it by making sure that the power stations had such vast stocks of coal that even the most prolonged strike would not cause the lights to go out.

So it turned out. Those most pleased by the outcome were probably the moderates in the trade union movement and the Labour Party, for whom Scargill was anathema. This time, the polls showed no benefit at all to the Thatcher government. But it was important nonetheless. Not just because a victory for Scargill would have been highly damaging, but because, just as the Falklands victory had exorcised the ghost of Suez, so the miners' march back to work in 1985 had exorcised the ghost of the fall of the Heath government in 1974. The threat that militant trade unionism could drive a democratically elected government from office had at long last ended.

These were the great achievements of the Thatcher years. The first duty of the state is, of course, to preserve the security, both external and internal, of its citizens: the promotion of prosperity comes second. But so far as external security is concerned, the successful ending of the Cold War and the dissolution of the Soviet Union was primarily the achievement of Reagan's United States, and the supporting role played by Thatcher's Britain, although not irrelevant, was minor - probably less important than that of the Polish Pope. And the threat to internal security from Islamic fanaticism had not yet emerged.