IN ANSWER to those who doubt whether we Yanks have ever really gotten over the separation anxiety suffered as a result of the Revolutionary War, I have two words:

"Masterpiece Theatre."

(Note the hoity-toity spelling of "theatre," an Englishism increasingly affected on this side of the Atlantic any time we former colonials want to sound less like tobacco-spitting hayseeds.)

If there's any better argument in support of our twisted emotions (a combination of admiration, guilt, arrogance and inferiority) regarding All Things British than "Prime Suspect," "Jeeves and Wooster," "Upstairs, Downstairs," "I, Claudius," "The Jewel in the Crown" and "The Six Wives of Henry VIII," I don't know what it is. And let's not even get into our whole unhealthy fixation with the late Diana Spencer (God rest her troubled soul).

Now at the Library of Congress and jointly sponsored by the British Library, the exhibition "John Bull and Uncle Sam: Four Centuries of British-American Relations" makes the absorbing, erudite and amusing case -- with archaic maps, drawings, books, wry film clips, pop music and assorted Anglo-American esoterica -- that, yes, we here in the U.S. of A. are still a bit hung up more than 200 years after the breakup with Mother England. But, hey, it takes two to tango.

After all, the Brits didn't exactly come out of this age-old love-hate relationship with their emotions entirely unscathed either.

Witness this telling clip from "Austin Powers: International Man of Mystery," playing near the entrance of the exhibition along with dozens of other archival film and video clips in continuous rotation on one of the several video kiosks located throughout the show:

A buffoonish American played by Tom Arnold, clad in the exaggerated Western regalia and 10-gallon hat of a cowboy, encounters Mike Myers as Brit superspy Powers, tricked out in his trademark Teddy-boy suit of red velvet and ruffled lace.

"That's some get-up," says Arnold, admiringly. "Are you in a show?"

"No," says Myers, smiling with vague condescension through a clenched set of rotten teeth. "I'm English."

"I'm sorry," responds Arnold, his face dropping in sympathy.

Don't be surprised if you encounter fellow museum goers laughing out loud at this and other A/V snippets illustrating the difference between the United States and Britain and drawn from such unscholarly sources as "Saturday Night Live," "The Simpsons" "Patton," "Frankenstein" and "Dr. Strangelove," as well as an interview with gay writer and storyteller Quentin Crisp (by his own description "one of the stately old homos of England").

It's exactly this point -- that the tables have turned dramatically, and are turning still, on the country of our founding fathers -- that is made so well throughout this exhibition. A sampling of cartoon depictions of Uncle Sam and John Bull is on display, tracing the subtle evolution over time of these two national symbols of the United States and Britain. In the 1800s, the rotund gentleman farmer from England seems to shrink in relation to his American counterpart, the onetime subordinate in the striped pants and top hat, while in the 20th century John Bull begins to increase in size again as a metaphor for the growing parity between our two nations.

Much of what else "John Bull and Uncle Sam" has to teach us is how our two countries have influenced and continue to influence each other in the realm of culture. In the beginning, of course, most of that wind blew westward from England. Now the current flows predominantly in the other direction.

They gave us Shakespeare, Charles Dickens and Rudyard Kipling; we gave them Washington Irving, Nathaniel Hawthorne and Sylvia Plath. They gave us Twiggy, Teletubbies, the Beatles and the Rolling Stones; we gave them Chuck Berry and the blues (where do you think Mick Jagger and other English rockers got the idea to shake their cans in the first place?). They gave us fish and chips; we gave them beer in cans.

On the humanitarian side, the British came up with our game plan for women's suffrage and abolition, while we had to show them how to conduct a civil rights movement. They sent us Scottish immigrants Alexander Graham Bell and Andrew Carnegie; in return, we showed them how to build skyscrapers, make motion pictures and use the typewriter. For years and years, we harvested their cotton; by way of thanks, we got Alfred Hitchcock, Monty Python, Benny Hill and the Avengers. We gave them our principles of assembly-line manufacture and, in a bit of poetic justice, they sold the Jaguar automobile to the Ford Motor Co.

The collaborative research on the structure of DNA between American biologist James Watson and English biophysicist Francis Crick (resulting in the 1962 Nobel Prize) is but one example of what can be accomplished by international cooperation.

The message that the cross-pollination is fairly equal is well taken, (although personally, I think we still owe them for Shakespeare). But the show's most inflammatory claim -- that the Brits may have been engaging in our national pastime even before we were -- is sure to provoke some baseball purists.

In a British children's publication from 1760, an illustration shows a suspiciously familiar-looking game called "base-ball" being played by young men in tricornered hats. The accompanying verse reads:

The ball once struck off,

Away flies the Boy,

To the next destin'd Post,

And then Home with Joy.

The presumption that baseball, for God's sake baseball, may be less American than apple pie (although the British probably invented that, too) is enough to start another revolution.

In all seriousness, though, as the exhibition makes clear in its delineation of our historical ups and downs, the relationship between our countries has a long history of being far from cozy, above and beyond that old unpleasantness about "taxation without representation." Tempers also flared during the Civil War after attacks were made on the Union by Confederate ships that had been equipped in British ports. And then again, just a few decades later, during the War of 1812, the British themselves stormed Washington, burning the Capitol and the White House in 1814 -- as attested to by the scars on the Truman balcony (mentioned by President Clinton in a speech to Parliament) and by the sole surviving volume from the original Library of Congress (on view here).

Well-known and obscure facts and figures fill the display cases: stats about the number of Irishmen who arrived in America as the result of the potato famine (over a million); about the number of Englishmen who participated in the California Gold Rush (20,000 . . . who knew?); about how the tune for "The Star-Spangled Banner" was lifted from the early 19th-century English drinking song ("To Anacreon in Heaven" . . . who doesn't know that?).

It's a dense, varied and in some ways conceptual exhibition. The all-but-illegible letter of condolence, for example, written by Queen Victoria to Mary Todd Lincoln on the assassination of her husband, is for the layman less interesting as an object to look at than as a subject for contemplation.

Its significance is important, because it crystallizes what is being said in "John Bull and Uncle Sam" very succinctly: i.e., that despite our sometimes different politics, despite our funny accents and incomprehensible slang ("two nations divided by a common language," in the words of George Bernard Shaw), despite our sometimes acrimonious dealings with each other and despite sometimes wrestling with feelings of insecurity, we are at heart all the same.

JOHN BULL AND UNCLE SAM: Four Centuries of British-American Relations -- Through March 4 at the Jefferson Building, Library of Congress, 10 First St. SE (Metro: Capital South). 202/707-4604. Web site: Open 10 to 5 Mondays through Saturdays. Free.