London — Drumming fingers on his desk, the editor of the BBC Polish service, Kris Pszenicki (pronounced ''pzniki'') talked about how to be believed.
''Of course, there is no such thing as objectivity,'' he said. ''Everyone makes value judgments. But we try to be balanced. We've been broadcasting to Poland for 43 years. We have the credibility of the World War II years. We are perceived to be independent of the government.''
''And,'' speaking slowly and carefully, ''we don't have editorials. The BBC as an institution doesn't have an editorial viewpoint.
''Oh, I can broadcast a commentary. But it has to be as balanced, truthful, and objective as I can make it, and it must be clearly signed.''
In any other institution the words might have a hollow ring. In the external services headquarters of Bush House in London, they ring true.
''We don't agonize over our credibility,'' says Peter Udell, head of the BBC's Eastern European services, including the Russian service. ''It's built into everything we do.''
Barry Holland, editor of the Russian service itself, agrees. ''There's a kind of gas in this building,'' he says with a grin. ''Invisible, but very much present. It's an atmosphere, if you like, the ethos of a balanced view.''
The Russian service has benefited enormously by talented emigres such as Alexander Levich, Georgy Ben, Yefim Slavinsky, and Zinovy Zinik joining the staff in recent years. It also thrives because, like other BBC language services , it can draw on the entire resources of the BBC, worldwide and domestic. Other Western external broadcasters are separate from domestic services.
''In Latin America, the BBC gained enormous stature after the war with 21 -part serializations of Don Quixote, and the voyages of Christopher Columbus, all done with special music and great flair,'' recalls Alberto Palaus, head of the Latin American service.
''Culture is the great thing in Latin America. Every politician wants to write a book. We kept our prestige through the years, and the Falklands war really boosted us. Nineteen radio stations kept calling us to find out what was really happening, from Uruguay to Mexico.
''Argentina tried to jam us but radio stations in neighboring Santiago and Montevideo weren't jammed, and they broadcast our reports right into Argentina. Our stature rose.''
The work of Messrs. Pszenicki, Udell, Holland, and Palaus are part of the mosaic of the BBC external services. They add up to credibility -- not a strident point of view, but a reputation, built up over many years, of dedication to reporting the facts as they happen, no matter how inconvenient those facts might be for Britain or its allies and friends.
None of these men said they felt the latest Voice of America concept of two-minute editorials giving government opinion was necessary or desirable for the BBC.
All said they thought credibility stemmed from the approach of many years. At the same time, none faces the anti-Soviet pressure of a Reagan White House: The Margaret Thatcher government is anti-Soviet, indeed, but the BBC is remarkably free from editorial interference.
And it remains true that Britain's decline as a world power in fact tends to add to its air of impartiality and credibility, even though it is a firm US ally.
In many parts of the world, it is easier for the BBC to be accepted than the voice of the United States superpower, although sometimes it works in reverse: Soviet dissidents, for instance, tend to prefer the VOA precisely because it is American and thus anti-Soviet.
News bulletins for all BBC language services are written in English by regional news desks in a central newsroom, then translated by programmers for individual countries.
The BBC principle is that each service should present the world as seen from London, rather than take the Radio Liberty approach and try to supplant the domestic radio service of the receiving country. Despite a constant shortage of budget, and offices scattered around the rabbit-warren, dowdy floors of Bush House in London, morale and professionalism are high.
Kris Pszenicki illustrated the balanced approach: ''In August last year, for two programs at the end of Solidarity's first 12 months, I was able to interview the chief government spokesman, Jerzy Urban. Even though the call went through 45 minutes late, Urban was still waiting.''
In Poland, the BBC service matters. Perhaps 71/2 million Poles, 1 in 5, listen to at least some of its 33/4 hours of programming each day (the three-quarters of an hour was added in December 1980 to provide more news of the Solidarity phenomenon.) ''We balanced him with the chief Solidarity spokesman, with Jacek Kuron the intellectual, with a lay (Roman) Catholic involved with Solidarity, and so on.''
Today, a phone call to Warsaw takes 36 hours. It is extremely difficult to obtain telephone interviews.
Soviet devices jam BBC Polish broadcasts from the western USSR, although a medium wave free from jamming can be heard at times.
The Polish service generates its own material for its listeners, but does not compete with local services better provided by Polish radio, such as sports. Most of its news and current affairs comes from translating regional desk material from English.
The Russian service produces a much higher percentage of its own material, at the initiative of its emigre staff. It ranges from interviews to feature programs, including an ''English diary.'' It offers quotes from the Soviet press 10, 20, and 50 years ago.
The Russian service is on the air every night in a five-hour block. Each hour is divided into 30 minutes of news and current affairs, and 30 minutes of features, including a great deal of cultural material.
Program hours went up by 30 minutes a day after the invasion of Afghanistan, another half hour when jamming began to keep out Polish news in August 1980, and still another half hour (a morning news program) when the five-hour nightly block began.
The Soviet audience is hard to guess. One Soviet estimate was as many as 40 million regular listeners, but even the VOA itself claims only 12 million.
In Argentina, Alberto Palaus says 200,000 listened to the BBC in Spanish before the Falklands war. He believes many more do now.
For many years, the BBC service to the hemisphere was four hours a day. Five days after Argentina invaded the Falklands it rose by an extra hour, and a month later it gained another 30 minutes as the Foreign Office waived budget ceilings.
Although extra staff was also authorized, it takes months to recruit qualified people, so the existing staff worked around-the-clock during the war.
Argentine jamming was uneven, and some frequencies were not blocked.
Second of four articles. Next: BBC for breakfast in the United States?