A new lease for the anglo-American alliance By Rushworth M. Kidder, Staff correspondent of The Christian Science Monitor

As chill political winds from the Russian steppes wither the buds of East-West detente, a new flower is sprouting from an old bulb: the anglo-American alliance.

Observers here see Prime Minister Margaret Thatcher's speech in the Jan. 28 House of Commons debate on southwest Asia as an affirmation of total support for President Carter's stance againt the Soviet Union.

The American public, for its part, has shown inreased interest in Mrs. thatcher, whom the Russians deride as the "iron lady" and accuse of trying to wear Sir Winston churchill's trousers. Last fall she articulated her anti-soviet and pro-chinese stance. Her visit to the United States in DEcember, and her strong reaffirmation of Anglo-American friendship, rang sympathetically across the nation.

The roots of this transatlantic friendship are deep, stretching back well before the two world wars. But as recently as last summer the British press happily caricatured President Carter simply as a well-meaning naif who got bitten by a rabbit and retreated to Camp David to lick his wounds.

Now, however, he is seen to have handled the Iranian hostage problem very well. And his hard line on the invasion of Afghanistan is seen to be justified by the strong condemnation of Russia from both the United Nations and the Islamic conference in Islamabad, Pakistan. This heightens the feeling of respect for his leadership.

The British press gave widespread coverage and positive comment to the President's Jan. 28 announcement of the 1981 budget, particularly approving his proposals for increased arms spending.

And the leader of the opposition, James Callaghan, followed Mrs. Thatcher's speech with his own firm support for Mr. Carter's position, esecially welcoming the plans for revitalizing the US armed forces.

Such responses may be volatile. Two months ago, says one American diplomat here, Mr. CARTEr was "in the doghouse," but "now he's a hero." This diplomat says his friends in the British Parliament tell him, "It's great to have us back firmly on the same side again." and they are pleased to be able to "have a good word to say for Carter for the first time."

The new-found unity is not surprising, according to William Rees-Mogg, editor of The times of London. He feels that Mr. Carter, like presidents Truman an Wilson before him, came into office innocent of foreign affairs adn needed time to take "the measure of the world."

But Britain and America, he notes, have always pulled together when facing a major crisis. "The actual bedrock opinion in each country is very, very similar ," he told the Monitor, adding that "we are, as De Gaulle said, the Anglo-Saxons."

One question raised by improving Anglo- American relations: Will it draw Britain further away from its European Community partners?

Britain's relations with Europe are not free from strain, which Soviet propaganda has sought to exploit. The French are still re British lamb to move freely across their borders.

And Britain is lobbying hard for a substantial reduction in its L1 billion ($ 2.2 billion) annual contribution to the EC budget. within europe there are also problems of fishing rights, North Sea oil sharing, and undisguised nationalism, sometimes manifested as subtle anti-Americanism.

Yet, the slowness of the continental countries to respond to the Soviet presence in Afghanistan contrasts sharply with the perceived decisiveness of Mrs. thatcher and Mr. Carter. Britain, alone among European nations, sent a top-level emissary (Foreign Secretary Lord Carrinton) to tour Muslim nations shortly after the invasion of Afganistan. His insights have no doubt been crucial in determining Mrs. thatcher's stand.

The impression remains that the center of Western leadership has rather quickly swung away from the Continent and toward the midAtlantic.