The talks here between British Prime Minister Margaret Thatcher and Soviet leader Mikhail Gorbachev were a highly satisfactory exercise in image building for both sides, though Mrs. Thatcher derived the most tangible benefit from the trip. With the prospect of an early general election in Britain, the prime minister's visit has undoubtedly reinforced her standing as a European leader. She had 11 hours of vigorous discussion with Mr. Gorbachev.
Thatcher's tough image was further enhanced by a 50-minute television interview in which, in the view of some Soviet and foreign viewers, she bested a panel of Soviet journalists. The news conference was screened uncut on late-night Soviet television.
The advantages for Gorbachev were equally substantial. The Soviet leadership is trying hard to overcome its old image of secrecy and dogmatism. Doubts are still voiced in the West about the sincerity of Gorbachev's call for radical change - and about the desirability for the West of successful Soviet reforms. Thatcher, a Western politician of irreproachably conservative credentials, essentially took the Soviet leader's side in these debates. She praised Moscow's ``courage'' in embarking upon changes.
Asked at the news conference if the West should welcome the new policies, she replied that ``a more open society with more open discussions and wider freedoms is in the long-term interest not only of the Soviet Union but of the West.''
These statements are important in practical political terms: Moscow wants to project the image of a country with which the West can work - both in political negotiations and in trade.
Thatcher's endorsement of the Gorbachev regime was not total - more time was needed before the West could completely trust Moscow's undertakings, she said. But, given her resolute anticommunism, even a partial endorsement carries considerable weight. Moscow now hopes that some of Thatcher's positive impressions will influence Mr. Reagan, her close ally, and other United States conservatives.
In his efforts to convince Thatcher that things were changing for the better, Gorbachev received help from Andrei Sakharov, the former dissident leader. Dr. Sakharov's support for reform, expressed during lunch with Thatcher, underlines - especially to doubters inside the Soviet Communist Party - Gorbachev's wisdom in allowing him back from exile.
On major issues such as arms control, the visit produced little of substance. The two sides were able only to clarify and restate their positions. Thatcher expressed optimism that an agreement on medium-range missiles could be concluded by the end of the year. But she noted that the two sides disagreed over short-range nuclear missiles. Moscow and London agreed to increase their trade and cultural relations. But the major benefit from the visit for the British was the boost to the Iron Lady's image.