As if imbibing classic British restraint with their gin and tonics, guests at a British Embassy reception last night discussed the ongoing Beirut hostage crisis with fitting diplomatic grace.

"We started getting in trouble long ago," said former secretary of state Alexander Haig about Middle Eastern terrorism. "In this business you get pregnant by inches."

"When your citizens, your family perhaps, are in danger, it's very difficult to realize that what you have to do is remain calm," said Sir James Eberle, former NATO Eastern Atlantic commander in chief. "The more one reacts, the more leverage one gives the terrorists."

Eberle and about 90 other foreign policy experts had gathered at the embassy to mark the 65th anniversary of the British think tank that Eberle directs, the Royal Institute of International Affairs, and the creation of the Chatham House Foundation, an American organization designed to support the Royal Institute.

The tone inside the embassy is not unusual these days, as almost everybody treads carefully.

"I just think we've said all we really can or need to on the subject," said Secretary of Defense Caspar Weinberger.

"I'm not giving any advice to anybody," said British member of Parliament and former prime minister James Callaghan, who is president of the Institute.

But, he said, "the principle is quite simple. Terrorists, hijackers, must not be allowed to succeed. The principal task of a state is to safeguard the security of the total community, not of some part of the community. That may involve some very difficult decisions."

Just how the state is to protect itself now, and in the future, remains undecided.

"I think every ex-bureaucrat in the nation is on national television telling the president how to do it," said Haig. "I went on just to tell him you cannot compromise with terrorists, not how to do it. That means telling Shiite extremists -- and I mean by that Damascus and Tehran and Libya -- that we're going to hold them responsible for the next act of terrorism."

Asked if "holding them responsible" might include military retaliation, Haig would only smile and say, "Hold them responsible -- it depends on the situation."

Not surprisingly, at a function for members of a foreign policy organization, the emphasis was on diplomacy rather than military action.

"I think you've got to look to tamping down the underlying political situation, the Israeli-Arab conflict that is the basis of the whole thing," said the institute's Middle Eastern specialist, Robert Belgrave. "The Israelis attempted a military solution, and it wasn't a great success, was it?"

While the Chatham House Foundation, named after the London home of the Royal Institute, is more immediately concerned with assisting the Institute and making it increasingly accessible to American scholars, Chatham House executive committee chairman Olin Robison said that during times of calm such institutions can foster relationships useful during times of crisis.

"There aren't many precedents in dealing with it," said Robison, president of Vermont's Middlebury College, of international terrorism. "It's obviously going to require an exceptional degree of cooperation between world governments which does not yet exist."

Speaking of the Beirut crisis, Chatham House board member Maureen White said, "This is where close collaboration and channels of communication with the allies is important. The weak links in allied relations -- i.e., our relations with Greece -- led to a flaw in our negotiating policy. They released the hijacker who didn't get on the plane for the sake of the release of the Greek nationals, negotiating a separate truce."

"Here we are all in this together," said Robison, "and they just do their own little private deal."