LONDON, DEC. 20 -- When John Major begins his first visit to Washington as Britain's prime minister Friday, Americans will see a cautious, low-key but self-assured politician whose foreign policy sounds a good deal like that of his famous predecessor but whose style is far less strident and dramatic.

Margaret Thatcher, whose 11-year reign as prime minister came to an abrupt end a month ago, had become a larger-than-life figure who constantly evoked Winston Churchill and the dark days of World War II in describing her vision of what the Anglo-American relationship ought to be.

But aides say Major, who at 47 is the first British prime minister too young to recall the war, will seek to emphasize something very different: a pragmatic partnership between two allies that share not only a common language but a common-sense approach to world problems ranging from the Persian Gulf crisis to free trade.

He also hopes to capitalize on similarities in style between himself and Bush.

"I think Americans will take to him," said an aide who spent three years working in Washington.

"He's a very approachable man," the aide said. "He will fit in naturally with the way Americans do business -- first names, working breakfasts.

"The style will fit in."

That informal style was on display last weekend in Rome, where Major attended his first meeting of the European Community's heads of government.

Analysts said that Major's go-slow approach to economic and monetary union was, in substance, almost identical to Thatcher's. But they said his unemotional, non-confrontational manner -- in marked contrast to Thatcher's often open hostility -- won points and signaled that Britain will not stand alone or seek to undermine agreement on these issues.

In the long term, many analysts predict, the end of British isolation within the EC will enhance relations with the United States. Until the gulf crisis loomed, the Bush administration had been subtly drawing back from Britain and relying more on Germany as the kingpin of Europe.

But a Britain that is comfortable inside the European Community and is also a major European player can serve as a conduit for American ideas and interests, analysts contend.

Major will get a brief but intense exposure to Washington on Friday.

After appearances on four morning news shows, he is scheduled to hold meetings with Secretary of State James A. Baker III, Vice President Quayle and Treasury Secretary Nicholas F. Brady, followed by a Capitol Hill luncheon hosted by House Speaker Thomas S. Foley (D-Wash.).

Then he and his wife Norma are scheduled to travel to Camp David for an overnight stay with the Bushes.

The main topics will be the gulf crisis, the future of NATO and the dispute between the United States and the EC over revisions to the General Agreement on Tariffs and Trade. Aides say Major will express unreserved solidarity on the first two and cautious sympathy on the third.

Britain is still getting used to its new prime minister -- and the new prime minister is adjusting to a post he had not expected to compete for for several more years.

At the first cabinet meeting after his surprise victory, Major reportedly gave his colleagues a big grin and said, "Who would have believed it?"

At home, Major has continued the same tough, unpopular economic policies he pursued as Thatcher's last chancellor of the exchequer as he attempts to steer Britain out of a deepening recession.

But he has tempered those policies with a more sympathetic and "caring" attitude toward a number of social welfare issues that plagued Thatcher during her last months in office.

The differences are relatively small: an $80 million settlement of a long-standing lawsuit involving hemophiliacs who contracted the AIDS virus from contaminated blood, more funds to house the homeless, a temporary suspension of radical reforms of the besieged National Health Service. But the symbolism is powerful.

Most of these changes were due to take place under Thatcher. The difference, an aide said, is that under Major they look voluntary and positive, rather than grudging and forced.

The public so far has responded with tempered approval.

The most recent Guardian newspaper poll showed Major's Conservatives retaining a slim two-point lead over the opposition Labor Party but a 47 to 25 ratio on the crucial question of who best can run the economy.

Given rising unemployment and the government's staunch refusal to lower interest rates, now at 14 percent, many Conservatives are delighted with the poll results.

"Everything rides on the economy," a cabinet member said recently. "If we can start seeing some real improvement in the first half of 1991, we'll come out fine. If things get worse, that's serious trouble for us."