A Pentagon spokesman said yesterday that Secretary of Defense Caspar W. Weinberger is a "devoted family man . . . the No. 1 married man of all time," and that a Sunday Times of London story intimating that there could be anything romantic between him and an English writer he has known for several years is "sentimental dribble, sheer trash."

The 64-year-old cabinet officer made the Times' Atticus column on Sunday when writer Stephen Pile wrote that Weinberger had "taken up" with a British "liberal" identified as Janet Morgan, who Pile said escorted him to a giant Hyde Park rally on nuclear disarmament last October on his way home from a North Atlantic Treaty Organization defense ministers conference in Gleneagles, Scotland.

Among questions the column raised was whether Janet Morgan's influence on Weinberger had "mellowed" him or lessened to any degree his "hawkish" stance on Europe or its defense.

Yesterday, deputy Pentagon spokesman Benjamin Welles said that it was assistant secretary of defense Henry Catto and not Weinberger who accompanied Morgan to the Hyde Park demonstration last fall. He also said suggestions that Morgan could influence Weinberger's philosophy were "ridiculous."

"What she could do is open up some fresh ideas to him in an intellectual give and take," said Welles. "He's interested in discussing with any intelligent person, male or female, such topics as relations with the Soviet Union, nuclear proliferation or European defense, and he's not averse to talking with an attractive, friendly and pleasant personality."

Welles said Weinberger first met Morgan, who edited The Crossman Diaries, "two or three years ago" while he was still an executive with Bechtel and used to attend the Oxfordshire think tank known as Ditchley.

The spokesman also said that Morgan, who is scheduled to write a biography of Agatha Christie, is "hoping" to do one of Weinberger but he doubted that the defense chief would sit still for a very long-range project.

"She's probably been hoping to inject into his thinking a little bit more about the European concepts and ideas of defense," said Welles. "She's been exerting what she likes to think is a liberal influence on him -- at least, that's the thrust of the story."

Morgan, an Oxford graduate, is "under 40," according to Welles. According to Atticus, she makes homemade ice cream "by the gallon" and is "a barrel of fun."

Weinberger made four trips to London last year, two in April, one in October and the fourth in December. Reporters joked about the frequency of the London stops. One London-based reporter said American officials told him that Weinberger had a favorite tailor there and also liked to visit the English countryside.

Weinberger was accompanied on most of the trips by his wife, Jane, to whom he has been married for 40 years, according to the Pentagon.

"He thinks the whole thing is ludicrous and just shrugged it off," said Welles of Weinberger's reaction to the Sunday Times report.