Ronald Reagan: "His acceptance speech at Detroit impressed even the millions of Americans who still visualized Ronald Reagan as an aging ham actor with a slight look of Mickey Mouse, a bizarre manifestation from the crazy state of California, possibly with sinister tendencies toward reactionary-fringe politics."

Jimmy Carter: "Jimmy Carter had no clear-cut opinions or policies."

Richard Nixon: "He was never able to live down the charge that some moral dimension was lacking in his character . . ."

These forthright notions -- and others going all the way back to George Washington -- are part of a new book put out by the people who gave us "Burke's Peerage," titled "Burke's Presidential Families of the U.S.A.," and they come from the mind of Marcus Cunliffe, an Englishman who specializes in thinking about America.

He is in fact one of the most distinguished Americanists around, at 57 a professor at George Washington University after 15 years of teaching American Studies at the University of Sussex. He works in a room almost completely lined with books about America, and the first thing everyone asks him is why. Why America?

The answers go all the way back to his school days, when he read Thurber and Stephen Crane and saw American movies, and to the war when, as a soldier, he saw American dead in Normandy and the Ardennes and watched "Flying Fortresses spiral into formation at dawn over East Anglia and come back in mid-afternoon from their daylight raids, singly, sometimes in dire trouble, barely able to clear the hedgerows."

Then there were the fellowships at Yale and Chicago and Washington and Stanford, the professorships at Harvard and Michigan, the American wife, the 30 years of living with this loud and inadvertently complicated people for whom the British have always felt a certain responsibility.

There's another reason, he pointed out in a recent paper: ". . . Secretly ashamed of big feet and gangling arms, I found that in the United States, where the skinny-gorilla physique was common enough, I was not misshapen but Lincolnesque . . ."

Marcus Cunliffe knows more about America than most Americans, and he has so much to say that he almost can't stand it. At the moment he is updating a major work on American literature "which has got a bit brown at the edges" and is halfway through a study of our concepts of private property as shaped by slavery, wild Indians, Western settlers and other exotica.

"You don't have that useful fiction, The Crown," he observed in an interview recently, "which in effect means public ownership. It can be quite handy."

Then there is the study on slavery and its relation to "wage slavery," the book on the American presidency and a steady flow of papers. He is preparing a lecture on imaginary wars, which will add another armful of books to the shelves. And he's doing another piece on George Washington, whose 250th birthday next year will be very big at the Smithsonian.

"There's not much new you can say about Washington. He has a ritual importance, rather like the words of the Mass. Lincoln and Jefferson's speeches have become sacred texts, but Washington has even gone beyond that."

Interesting that the Lincoln and Jefferson memorials contain statues while Washington's is simply an abstraction.

Recently, the hero worship has wilted a bit, he noted. People are asking why the Father of his Country was childless, and some rude fellows have suggested that maybe he was a woman, with his narrow shoulders and wide hips. But that's another story.

"The English have always had a special interest in America. After all, they had something to do with its constitutional system, and they're interested in its workings. Also, they're curious at this part of the Commonwealth that went wrong."

Americans, on the other hand, seem to show little curiosity about a country whose history could prove quite instructive: "Perhaps they don't want to think about the Thatcher government and what that means here. It might be more consoling for Americans to see what's happening as a phase that all the constitutional governments are going through, and not some personal doom."

Cunliffe is concerned about "the newness of newness," the growing fashion for the U-turn, the tendency of each new president to swing 180 degrees and reverse the policies of his predecessor -- which themselves were a reversal.

"Perhaps," he writes in the Times Literary Supplement, "America is now at the stage of reversing itself in a number of fields. The current repudiation tends to be of the previous generation's dogmas, and also of the very idea of planning. Proposition 13 and Milton Friedman appear to be in the ascendant over the Welfare State and Keynes of Galbraith."

The insistence on newness for its own sake depresses him, as does the changing texture of living in this country. "I know personally of eight cases of muggings and robberies here, including one rape on the same day the hostages came back, that famous day of love and friendship. I'm depressed at the incompetence in running them. It's high time the Americans stopped being so complacent about these things. I mean, the idea that gun control simply can't be done. You'd think the federal institutions were some sort of feudal, medieval contraption, totally ineffectual."

He is worried about the economy too, but at the same time he isn't ready by any means to write off America. "It has a great fund of energy," he says, "and a certain good sense, a skepticism. I like that."