President Reagan's latest arms control proposals have been welcomed by the NATO allies as a timely gambit that reaffirms American willingness to make early progress at the forthcoming superpower summit in Geneva.

The rapid American response to the sweeping Soviet offer of a 50 percent reduction in strategic nuclear weapons has eased apprehension that the Reagan administration risked being upstaged by Soviet leader Mikhail Gorbachev's clever appeals to overriding concern in European capitals about the fate of arms control.

In his United Nations speech 10 days ago, Reagan disappointed some allies by renewing his strident rhetorical attacks on Soviet behavior. Even after the president assured the leaders of industrialized democracies in their New York consultations that he would submit a constructive reply to the Soviet arms offer soon, there were nagging worries that Reagan's posture toward regional conflicts such as Afghanistan, Angola and Latin America would diminish chances for a fruitful discussion on ways to reduce the nuclear threat.

But the sudden narrowing of the gap between U.S. and Soviet positions on offensive nuclear forces has buoyed European hopes for a conceptual breakthrough in arms control. And with speculation rife that Secretary of State George P. Shultz will seek a second summit when he visits Moscow this week, the Western European allies are now assessing the potential effects of an intensified East-West dialogue.

In London, a Foreign Office spokesman acclaimed the new Reagan proposal and urged the Soviet Union to respond through real and earnest negotiations. The West German government said the latest U.S. offer reflected the allies' views and "opened the door" for compromise.

The deft maneuvering in Washington and Moscow to steal the spotlight in advance of the Reagan-Gorbachev meetings Nov. 19 and 20 has awakened hopes in Europe that stiffer competition between the superpowers over their respective images among allies and the world at large could yield unexpected benefits for individual countries and for East-West relations in general.

The resuscitated U.S.-Soviet contest for hearts and minds also has led some European allies to believe that their influence may now loom greater in Washington than seemed possible before Gorbachev came to power last March.

According to foreign ministry officials in Bonn, Paris and London, the unusually good display of alliance solidarity in recent months has derived in large part from a general recognition that Gorbachev's leadership has ushered in a more subtle and effective brand of Kremlin diplomacy, thus posing a more formidable challenge than in the past.

The Reagan administration, as the allies see it, now realizes that it must show greater flexibility than in recent years, when a succession of weak and sickly Soviet leaders paralyzed Kremlin policies.

The virtually unanimous support among the NATO allies for a strict view of the 1972 Antiballistic Missile treaty is credited widely with having enabled Shultz to prevail over Pentagon advocates of a looser interpretation. West German Foreign Minister Hans-Dietrich Genscher, echoing the views of many European allies, describes the ABM treaty as the "Magna Carta" of arms control and believes that any redefinition of its terms by the United States could impair transatlantic trust.

West German Chancellor Helmut Kohl, who has tried persistently to bolster his political stature by stressing his friendly relations with Reagan, repeatedly has claimed part of the credit for convening the Geneva summit and encouraging more regular summit meetings in the future.

For the Bonn government, consistent contacts between the United States and the Soviet Union are considered the best way to enhance relations with East Germany.

West German newspapers already are speculating that East German leader Erich Honecker will make a long-expected visit to his birthplace in the West German state of Saarland that he was forced to cancel last year because of opposition in Moscow.