"All right then, meet me Wednesday, no, it had better be Tuesday in the bar of the Five Casks Hotel. The big one on the corner of the marketplace, not the little one by the river At 12:30. Goodbye."

"Wait. Don't hang up What town?"

"Oh yes The town of - "

It was a furtive business and getting more furtive by the minute, this meeting with a man whose name and whereabouts are a carefully guarded secret. It was not a ransom dropoff. Nor was it a contact between secret agents. It wasn't even a new leak. It was an appointment with the world's most popular veterinarian, James Herriot.

Herriot is the pseudonym of the author whose bestselling books, "All Creatures Great and Small," "All Things Bright and Beautiful" and "All Things Wise and Wonderful" - 27 out of the last 29 weeks on the bestseller list, eight of them in first place - make the hard work, long hours and frustrations of a rural veterinarian sound like a continuous idyll. Herriot's compassion for his animal patients, whom he treats not as so much livestock but but as individuals with distinct personalities, is exceeded only by his compassion for his own species and delight in its vagaries. His Yorkshire is peopled with a Dickensian collection of characters. There are his partner, the competent, highminded, and quixotic Siegfried, and his playboy brother, Tristan. There are the overpowering Miss Harbottle, the sadistic and lecherous Angus Grier, Mrs. Pumphrey, who carries anthropomorphism tp the extreme of sending sherry and brandy to her convalescing pekingese, a caprice with obvious benefits for the veterinarian. There is Mallock, the local "knacker," whose business it is to dispose of unmarketable carcasses, and whose own children play in carrion as contentedly as other people's children build sandcastles. There are the farmers: always an eccentric, hardworking breed, some tightfisted and unscrupulous, others generous when they barely have enough for themselves, often courageous, occasionally vicious, usually critical, imbued with folk wisdom and absurd superstition.

And there is Herriot himself, wresting amusement from his own mistakes are misdiagnoses: his bungled courtships; the cow that he was certain had a pelvis and would never get up again who proceeded to prove him wrong and haunt him for year, demonstrating that whereas doctors bury their mistakes, veterinarians are dogged - if not cowed - by theirs; and the pet parakeet that died of fright in his hand (and for whom he quickly and quietly substituted another). He decribes his triumphs too: the births, the citres, the inexplicable miracles.

It hadn't been easy to get his phone number, and it wasn't easy to get to him. In fact when I finally stepped off the train, I was pretty sure I was in the wrong place. The platform was in the middle of nowhere; there was no town anywhere around. I thought of loitering around a phone, waiting for it to ring and a muffled voice to direct me elsewhere, but I couldn't find a phone. There was a ladies' room, but its interior at first only increased my apprehension. It couldn't be real; it had to be part of a Victorian ghost town. It was a huge room with a cold marbel-fronted fireplace, straight chairs and a dining table covered by a purple plush cloth - all wrapped in layers of dust. And no plumbing. Then, behind a door, I found two sure signs of the 20th century: a long and explicit WARNING about the dangers of venereal disease . . . and a pay toilet.

With renewed hope I banged at the TICKETS AND INFORMATION window, and eventually a face became vaguely visible on the other side of the grimy glass. "Is there a town anywhere around here?"

"That way," he pointed. "A mile and a half."

And so it was - exactly as Herriot had described it: the austere brick buildings, snowdrops blooming everywhere, the wide cobblestone marketplace. There were even two hotels called "The Five Casks." (That in a tiny community with scarcely two hotels both should have the same name didn't surprise me in the least. I had been in this country long enough to learn that when the English find a name they like, they stick with it. I had already spent a day in Hampstead hunting for a Frognal address on Frognal Close, Frognal Way, Frognal Court, Frognal Gardens, Frognal Lane, and Frognal Rise.) So I went into the bar of the Five Casks Hotel at the corner of the marketplace and waited. And he appeared.

There I was, face to face with the elusive James Herriot. What a triumph! Well, not quite. Tourists pour in torrents through his "surgery" (clinic). In fact I appear to be the only person who's even had trouble finding him. He's become one of the stops on the Grand Tour now, along with the Tower of London and Winchester Cathedral. No doubt he'll be listed in the next edition of the Blue Guide. ". . . An alternative route from London to Edinburgh passes through the 18th-century market town of - . Well worth the visit to see the surgery of James Harriot. No addmission fee. Closed Sundays . . ."

He said with a wan smile, "My cover's been blown."

To use the other side of the hunting metaphor, he's a sitting duck. Most celebrities can escape a too-clamorous public by taking a villa on the Riviera or moving to a country estate surrounded by an electrified fence. But Herriot's life's work is caring for the animals in and around the town where he lives. He has office hours twice a day. "They come in hundreds to the surgery, snapping their pictures. But it's not a show, not an exhibition. It's a room full of sick animals and their worried owners. Naturally, some people get annoyed. And it's exhausting having the flashbulbs flashing. And embarrassing. And they don't just take pictures; they want to visit, to spend the day with me.

"They are paying me a great compliment, I quite realize that. At the same time it is putting a tremendous strain on me. I'm very busy. I used to work seven days a week. For the past years I've only worked six, but of course I work at night too. Sometimes all night."

"The writing has dwindled away. I'm bombarded with thousands of letters and books. I don't have time to read the books. To some people I send form replies. But others must be answered personally, so when I get a few minutes to spare I write letters."

He was sandwiching in this interview during his lunch hour. We had moved to the hotel restaurant - quieter than the bar - and he chatted with the overworked waitress about how it felt to be rushed, drank a pint of bitter, and put away a cheese omelet and "a bit of turnip." He was dressed in his "working clothes": a beige cardigan sweater with sagging pockets, brown baggy pants, and a nondescript shirt and tie. His gray and white hair straggled down his neck and under his collar. He obviously didn't take time for haircuts. He had a kindly roundish face with gentle features and the ruddy, silk complexion that people on this island get when they spend time outdoor - skin without blemishes, seemingly without pores. It was uncanny the way he looked, acted, was the character of his books. Only the name had been changed. He said, "I use my life as a framework for telling stories."

He came to writing relatively late, and for the simple reason that he had a lot of good stories to tell. "Amusing things happen with animals. I talked about writing a book for years and years. Then one day my wife said, 'You'll never write a book.' I said, 'What do you mean?' She said, 'We've been married for 25 years. You're 50 year old. People don't suddenly start to write a book at the age of 50.' That rather settle it. I got down to it. I wrote while watching television at night. If I'd gone off in a room alone to write, I should never have seen my family. I wrote in among them for 15 minutes or a half hour at a time. I've never written more than an hour at a time in my life. The sweat is getting it down in the first place. Working over it is the part I like."

Before he bacame a writer, he was a reader. "I'm a great reader. I read everything. Especially Americans. Hemingway, Fitzgerald, Salinger, Budd Schulberg. I like Huxley, Conan Doyle. I read historical biographies, Richard Aldington, and histories. Nothing is better than a well-written history. But now I don't have time. I can only read in bed."

He has no shortage of things to say: "So far I've only written about the old black-magic days, when I first qualified. An the funny old cures. After the war everything changed, with the new drugs - antibiotics, steroids - and the new treatments and operations.Quite a fascinating change in vet practices. The caesareans. Doctors bring their patients to the hospital for complicated surgery, but the vet has to do it in the barn or in the fields. And I have some funny tales about artifical insemination. That's relatively new. It used to be that any old bull would do, to keep the cows producing milk. Nobody thought about increasing the quality of the livestock. You know artificial insemination here is handled by a government agency - the Milk Marketing Board. That's why the farmers call the man who comes around 'the bull in the bowler.'

"My books have information in them. People can enjoy them and learn a bit, too, about animals."

No one would dispute that he knows his subject inside out. In fact many of his most graphic descriptions are of insides coming out: billowing and seeping and exploding from a varity of natural and surgical ofifices. He doesn't shy away from accurate names and clinical details. Toxemia, dysentery, milk fever, eversion of the uterus, prolapsed uterus, distemper, hematomas, papillomas, lipomas, lymphosarcomas, carcinomas, epilepsy, pyloric stenosis, pyrometritis, urticaria are practically household words when he's finished with them. With a proper index his books could serve as a "Dr. Spock" for animal owners, alerting them to symptoms that can be treated casually and symptoms that require immediate attention. This approach enables Herriot to avoid the bete noire of animal-story writers: sentimentality. "I treat them from a vet's viewpoints, with a desire to help the animal, to cure it, not to look on it with a sentimental eye."

He intends to continue the saga of his own life: His children are grown up. His son is in practice with him; his daughter is an M.D. His partner, Siegfried, has long since ceased to be a bachelor. He too has a son and daughter. Tristan became an eminent public official and only recently retired.

And there will be entirely new subject matter. "Until the book ("All Creatures Great and Small") came out, I hadn't led an adventurous life. I hadn't traveled. I hadn't been out in the world. My life has changed. I've had a number of interesting encounters. I have several hundred headings written down. If only I have the time to get down to writing them."

His practice has changed too."A lot of our work is with dogs and cats, much more than it used to be. We have two surgeries a day for pets. The pet population has grown tremendously. The affluent society. Very few vets have a purely agricultural practice these days. It's mixed. I like small-animal work, but only as a change from the other. I wouldn't want to be indoors all the time. People have more money so that have more pets. Pets are an emotional outlet. Something to love increases a person's happiness; that's fundamental. People have a caring instinct; they like to look after something. And a cat and dog are utterly dependent creatures. When you think of all the lonely people . . . You're never really alone if you've got a cat or a dog. If a person has one dog and loses it, I always say get another right away. Even if they think they don't want to, they're always glad they did."

One of Herriot's own dogs, a Jack Russell terrier named Hector, died recently at age 14 ("Terriers have a lot of character. They tend to go their own way.") His other dog, Dan, a 12-year-old black Labrador, is in no sense of the term a spring chicken.

"You know mothers blame me becuse their children can't get into veterinary school. They write me irate letters. But it's not my fault. This trend was growing long before I started ot write books. When my son went to veterinary scool 15 years ago, it was extremely difficult to get in."

Though he was astonished by his success ("I only wanted to get a book published"), perhaps he shouldn't have been. After all, he does make use of two-thirds of the Lincoln's Doctor's Dog formula (the apocryphal title invented to cover the most enduringly popular thems in American literature: the Civil War, medicine and animals. Too bad he doesn't practice in Lincolnshire instead of Yorkshire).

"The book didn't take off in England until after it was a best seller in America. My daughter suggested calling it "Ill Creatures Great and Small," but the American publisher thought that was too flippant. Americans have a less flippant attitude toward my work than the English. Here it's sold as humor."

The books are marketed differently in England. There are more of them and they're shorter. They have cartoons on the covers and such titles as "If Only They Could Talk," "It Shouldn't Happen to a Vet," and "Let Sleeping Vet Lie." They're referred to collectively as "the vet books." The American titles are taken from a verse by Cecil Frances Alexander. (Herriot was not aware that the English translation of Colette's collected animal stories is also called "Creatures Great adn Small.")

But if the books started off slowly in England, they're wildly popular now, owing at least in part to an ongoing BBC serialization. The first book has already been dramatized on the Hallmark Theater in the U.S., and a new film," "All Things Bright and Beautiful," will be released in the U.S. in June.

Herriot is very much in demand. "I get a lot of invitations to go places, to give lectures. But I can't go. I can't leave the practice. I did two publicity tours of the States, but now I'm declining all invitations. I just can't do it. I've stopped public speaking and visiting I've cut that right out of my life. You can't treat sick animals when you've got jet lag."

"A very dangerous trade, ours," is the way he sums up being stepped on by cows, leaned on by Clydesdales, kicked by stallions, crushed by bulls nipped by fetal pigs, and bitten by bitches. Yet he looks completely unscathed. Only his age (61) troubles him "In the large-animal work you accumulate vast knowledge and experience, but with all that skill, you have to face your physical limitations. It's annoying. Other people, when they become expert at a job, can just go on doing it. It gets easy for them. But I've had to learn to husband my resources. I get the farm lads to do the pushing and pulling. But I'm fit, thanks to my job." He has a slight build, a young man's body, without an ounce of flab.

And one respite from the pressures of fame is still open to him. He gets in his car and makes his rounds of the countryside. "The farmers don't care who I am. If I'm James Herriot or George Bernard Shaw or Charles Dickens, it's all the same to them - just as long as I cure their animals."