This year we pass Dr. Spock in the total number of books sold," says Ross McWhirter, 49. "And we'll probably outsell the Bible the year after that," adds Norris McWhirter, also 49 but precisely 20 minutes the older of the two. "Hard to be precise about the Bible, you know," muses Ross. "Oh yes," responds Norris, "no copyright figures and all that."

So, in a constant, staccato, serve-volley-placement-point style, speak the McWhirter twins, authors of the Guinness Book of Records whose 21st edition is due for U.S. publication late this month. Past editions have sold a worldwide total of 21 million copies, and the McWhirters expect their newest version to go over the five million mark. Taking this anticipation by the hand, they have recently been on the road, doing a half-dozen radio and TV shows a day, all the while demonstrating an apparent infinite ability to remember trivia from the book, from the longest human walk on hands ("871 miles, from Vienna to Paris in 1900") to the most common name in the world ("Chang—there are about 75 million of them").

Some researchers are fascinated by ESP. For the McWhirters it is "est"—any word ending with those three magic letters, whether it be oldest, fastest, biggest, smallest, brightest or dumbest. "You get so that any word ending in 'est' jumps out at you when you read newspapers or magazines," says Ross. Tracking down superlatives, verifying and codifying them, and putting them between the covers of what is arguably the most fun and fact-filled annual compendium in the world, has become a life's work for the twins.

The new edition of the Guinness series will be chock-a-block with more than 20,000 authenticated records—everything from the oldest nightclub in the world, "Paris' 'Le Bal des Anglais' founded in 1843," to the rare talent of Frank Keith of Naperville, Ill., who can "write decipherably, backwards, upside down, laterally inverted (mirror style) while blindfolded."

"Each volume is an immense improvement over the one before it," says Ross. Norris, inevitably, adds: "Just changing to metrics alone means thousands of additions." Ross comes right back: "When the British government redistricted the U.K. we were compelled to make more than 5,000 geographical changes in the text."

New records this year? "Pioneer 10, of course," says Ross. "Going 78,000 miles an hour now and ever faster. Sets several new records every minute." "Don't forget our Mr. LaMothe," adds Norris. "Jumps from 40 feet into 12" of water, dives in curved, like a banana" (PEOPLE, April 22). Ross returns with, "And we must mention that lad who can do the decimal equivalent of [pi]r2 to 15,000 places without making a mistake. Remarkable, for those are completely random numbers."

The McWhirters are to odd fact-fanciers today what Robert "believe-it-or-not" Ripley was to the generation growing up in the '30s. "That Ripley," says Norris, "used the greatest title in the world. His facts didn't have to be correct, just interesting." "We authenticate everything," Ross contributes. "We believe nothing unless we can verify it in some way. All those 150-year-old and 160-year-old Russians? Rubbish. They're all Georgians. Stalin was a Georgian. Liked to boast his people were a super race. So the local commissars began adding years on to oldsters' lives at census time to build up the legend. We can't prove anyone has ever lived for more than 113 years, 124 days and so that's the record."

The left-handed McWhirter twins are unmistakably from the same mold—both gray-haired, sharp-featured, left-handed. Norris will begin a sentence which Ross finishes. Ross quotes the height of a record tree, Norris tells you the dimensions of the forest it's in and the 13 unique animal species in the surrounding area. Norris tends to concentrate on the more mathematical records. Ross digs into the sports and legal championships. On the phone they sound identical. "Actually, we need a triplet," says Norris, complaining about the seven-day-a-week goldmine in which the two find themselves digging. Ross and Norris each live less than ten minutes from their suburban London office where they sit side by side at identical desks, dictating 60 or 70 letters a day into machines and organizing the workload of their earnest staff of 14. The office is lined with files into which are packed the letters, news clips and documentation backing up the records going into each successive volume.

"I was born on Aug. 12, 1925 at 7:40 p.m.," Norris says firmly, "and then Ross came along precisely at 8. The record is fully authenticated, of course. Mother was there at the time." Ross, never at a loss for yet another fact, adds, "In England, all twins must have the times of their birth on their birth certificates—to sort out who qualifies as 'first born' in wills, passing down of peerages, things like that."

While other British lads grew up reading Winnie the Pooh or Biggies, the young McWhirters cut their eye teeth on facts, facts, facts, drilled into them by a remarkable father who was the only Fleet Street journalist ever to edit three British national newspapers. The twins estimate they looked through a hundred newspapers a week "and then when we wanted to relax we'd go through the almanac looking for something new we didn't know."

World War II separated the McWhirters for the first time in their lives. Both joined the navy, and the only time they met during the war was when their two vessels collided in the Malta harbor. When Hitler was defeated, the two went to Oxford, Ross reading the law and Norris economics. Good school athletes, they earned their blues on the Oxford track squad, forming part of a record-setting relay team.

Coming down from Oxford in 1951, the twins became professional researchers, setting up business in a Holborn garret. For three years, they eked out a precarious living and then a missed shot, aimed at a golden plover on a Scottish grouse moor, started a chain of events that could make them the best-selling nonfiction authors in the world.

The errant shot was fired by Sir Hugh Beaver, then managing director of Guinness, the English makers of the most widely consumed stout in the world. Beaver grumbled after missing his winged quarry about it being "the fastest game bird in the world." "Not so sure about that, old chap," another gunner in the butts murmured. By the time the frustrated Beaver got back to the lodge he was intent on proving his point—and found there wasn't a book about that contained the necessary information.

Slowly, an idea hardened in the stubborn brewer's mind. All over the world, Guinness, coal-black and delicious, is served in pubs and bars where men of strong opinions argue about everything from the fastest heavyweight knockout on record to the number of troops that went ashore on D-day. Often the arguments were being settled only with fists or the knob of a billiard cue. What about a book—a Guinness book—that a barkeeper could reach for to say, beyond argument, which game bird in the world flies fastest? When he went to his office on Monday, Sir Hugh summoned a junior executive and ordered him to report back with an author-researcher to produce such a book of records. The young executive was an old school chum, Chris Chataway, and he eventually presented Sir Hugh with a brace—the McWhirters.

"We were interviewed in their London board room," Norris recalls. "No waiters," adds Ross. "Served yourself from a sideboard. They could say anything they liked. Be as caustic as they wanted in their grilling of us." The twins, still in their 20s, won every round. A director asked piercingly if the two could tell them the broadest river in the world that freezes? "The Ob, of course," Ross answered casually. Sir Hugh mentioned he was on his way to Turkey shortly. "Interesting language, Turkish," Norris murmured. "Only one irregular verb." Finally, they broke the bad news to Sir Hugh. "Sorry sir, but the golden plover—the Pluvialis apricaria to label it correctly—probably went over your butt at less than 60 mph. The spur-wing goose—or Plectropterus gambiensis—has been clocked at 88 mph, in an escape dive." The board capitulated, agreed with Sir Hugh's plan to hire the twins and left the luncheon thinking that the harebrained project would probably take a couple of years—if ever—to move from drawing board to printed book. Instead, the twins worked night and day in an intensive 16-week spurt and came out with a book that was printed in time for the 1955 Christmas sales season. Since then, the twins have come to own a large part of their publishing enterprise.

"Newspapers and magazines are probably our most important early warning system," Norris explains. "They tell us where and when records might have been set." "But then we authenticate the marks ourselves," Ross adds. "We have a pen-pal relationship with libraries, museums, record keepers of all sorts in about 150 countries."

They've developed little strategems to ferret out the facts they want. "You never, never write to Professor Gomez of Mexico City University and ask him what's the biggest meteorite ever to have hit the earth even though he's the expert in the field," Norris says. "He won't answer your letter. What you do is write him that his arch rival, Professor Delon of the Sorbonne, says that unquestionably it was the Siberian impact of 1908, and would he confirm it? Immediately you'll get back 20 pages from Gomez on all the impacts before and after Siberia which were much more significant. It's a trick of the trade—works every time."

When not fact-ferreting, the McWhirters have managed to marry, raise families, even run for seats in Parliament. They both stood as Tories in the 1964 election, both pulled over 19,000 votes and both lost. They pop up from time to time on children's TV, fielding questions from the moppets. Says Ross: "There's always one kid who asks, 'Who's got the longest nose in the world, then?' I do wish we'd get an answer to that one."

And what is the twins' most interesting investigation right now? Says Ross, "The youngest person ever to get an Olympic Gold Medal. He was probably under 10." Explains Norris, "It was the cox-and-four sculling competition in the 1900 Olympics in Paris. The Dutch crew unexpectedly found itself in the finals. They decided to go all-out for a win, fired their pudgy coxswain, picked a French boy off the bank and put him in the scull's back seat for a free ride. They won, the boy got a Gold Medal, and now no one knows his name, age or where he is." "If you know, we're at Guinness Superlatives, 2 Cecil Court, London Road, Enfield, Middlesex," adds Ross. "Write us. We'd really like to get that lad's name in the book."