THE workings of a nation can be like a vast unwieldy machine. It has many different wheels that function apparently independently of one another until a moment when suddenly they mesh and a number of things happen all at once.The wheels of Britain, for instance, include a domestic political wheel, a European Community wheel, and a Group of Seven wheel. Over the past year, these wheels have connected in such a way as to propel a man once seen as a mere prot of Margaret Thatcher onto the world stage as a leading voice of the West helping to defeat the Soviet coup. John Major was the newly appointed chancellor of the Exchequer last fall at the time of the eruption of a party leadership row that was partly about Mrs. Thatcher's policy toward Europe but also about whether it was time for her to move on. When the dust had settled, Mr. Major was the new party leader and prime minister. It being Britain's turn to head the Group of Seven major industrial nations, during the coup Major had an opportunity to show the world what kind of a leader he was. He has continued this role with his visits to Maine, to meet with President Bush; to Moscow; and to China, to give the Beijing leadership a frank earful on human rights. Part of leadership is simply being there. Major was there the morning of the coup, forthrightly denouncing it in an informal press conference with reporters camped out before that front door that bears one of the most famous house numbers in the world. He didn't thunder, but he didn't need to; events were providing the thunder. The leader of the opposition Labour Party, Neil Kinnock, by contrast, was not there. He was on vacation in Italy; the ever fair-minded BBC represented him with a still photo and a sound bite taped over the telephone, but it wasn't quite the same thing. Major, meanwhile, was in touch with Japanese Prime Minister Toshiki Kaifu to make sure he felt included in discussions. And even at a time when the Soviets had a diminished capacity for mischief in Eastern Europe, Major made a point of calling leaders there to assure them of support. He knew that if he had been in the shoes of those leaders, he would have been worried. His most important reaching out during the crisis, of course, was his telephoning Russian president Boris Yeltsin. The case has been made that what turned the course of events in the Soviet Union was not so much the multitudes of protesters, heroically brave though they were, as the behind-the-scenes negotiations of democratic leaders like Mr. Yeltsin. When Yeltsin said in an American television interview that his conversation with Major had been a factor in persuading the hard-liners to abandon plans to storm the Russian parliament, it hurt Major's standing not a whit. Yet Major tempered his forthright action with a realistic assessment of what leverage the West did have. The coup collapsed so mercifully swiftly that we may need to remind ourselves how inevitable and irreversible it seemed, for a few awful hours at least, given Soviet history and the resignation of the people. To borrow some terminology from the Harvard Negotiation Project, Major was arguing on the basis of interests rather than positions. He made clear his preference for Gorbachev's return to power, and was adamant on the need for the West to insist on the (apparently) deposed Soviet leader's health and safety. But he avoided being pushed into a position he might afterward regret. He stressed that the long-term interest of the West was in supporting reform, and that time was on the side of that process. When pressed at one point as to whether the leaders of the West might have to resign themselves to dealing with the putschists, the prime minister invoked Churchill's comment he would talk with the devil himself if it served the interest of Britain. If Major were going to let himself be cast as a wimp, it would be in the company of that other great wimp in British statecraft, Churchill. Not bad for one they call the "grey man."