The second person to buy a copy last night had been Secretary of Defense Caspar Weinberger, the first had been his bodyguard.

"Mr. Richard Smith," said Susan Mary Alsop, busily signing "Yankees at the Court" about "the first Americans in Paris," her latest literary effort to be published. In between inscriptions, she fretted a little.

"It's a very expensive book $17.95, Doubleday . I don't think Secret Servicemen are paid very much," she said.

A shortage of money didn't seem to deter Weinberger.

"Maybe I could open an account?" he ventured to Jean Waterhouse, rattling off his mailing address at the Pentagon.

Among the crowded shelves of the tiny Francis Scott Key Book Shop, Weinberger found not only two other books to charge to his new account but a syndicated columnist, Joseph Kraft.

It had been author Alsop, though, who first brought up the Falklands with Weinberger, a neighbor of hers in Maine. "But he said the only news is that the weather is so bad there," she said.

British Ambassador Nicholas Henderson and his wife came by on their way home from a black-tie party but didn't volunteer anything on the Falklands.

Meanwhile, tout Georgetown assembled at Alsop's feet, many of them also authors, such as Cynthia Helms with her husband, former ambassador and CIA director Richard Helms; William W. Warner (who wrote "Beautiful Swimmers"); Sondra Gotlieb with her husband, Canadian Ambassador Allan E. Gotlieb; and Lucy Moorhead with her husband, former representative William S. Moorhead.

"I've come to buy film rights to Susan Mary's book," said George Stevens Jr., chairman of the American Film Institute.

Before Weinberger left, he'd found two more books to add to his new charge account.

"I'm not sure the defense budget will allow that," whispered Bill Moorhead.

The Canadian ambassador, however, upstaged everybody by shelling out $17.95 in cash.

"Don't bother with the tax," said saleswoman Waterhouse, while Martha Johnson, who has owned the shop since 1939, and Isabel McDonnell, who runs its lending library, looked on from the sidelines. "You're a diplomat."