Herriot's Yorkshire

''We tramped through Swinnergill and over Melbecks Moor to Gunnerside Gill'': place names with this percussive northern sound could only be in one part of the world - Yorkshire. The sentence is, in fact, taken from a delightful book, by that most famous of country veterinarians, called ''James Herriot's Yorkshire.''

Not only have Herriot's books made him widely known and loved, but ''his Yorkshire'' - the North Yorkshire of Swaledale and Coverdale, Thirsk and Askrigg and Arkengarthdale, York and the Hambleton Hills, Sutton Bank Top (the ''finest view in England''), and as far east as the fishing town of Whitby - has become familiar for the first time through his books and the films and the television series made from them to thousands of people abroad.

Come to think of it, Herriot himself is ''from abroad'': he is a Scot, though he has spent all of his working life here. Ask a Yorkshireman about the Yorkshire countryside and you might, perhaps, receive a guarded answer actually disguising a secret pride of the fiercest and highest sort.

Ironically, it has taken a generous Scotsman to articulate this pride. He puts his abject admiration simply enough. Of his first encounter with the Yorkshire Pennines he writes: ''I suddenly found myself in a wonderland.'' Of gazing down at the River Swale, he recalls ''wildness and solitude breathing from the bare fells, yet a hint of softness where the river wound along the valley floor.'' And of the remote, open moorland: ''. . . it is up there on the empty moors with the curlew crying that I have been able to find peace and tranquillity of mind.''

This wonderland is now the subject of a tour specially designed for Americans eager to see ''Herriot country'' firsthand. In 1982 three 7-day programs are offered, starting and ending in London, in June, July, and August. Full details can be obtained from Susie Worthy at R and I Country Tours, 138a Piccadilly, London WIV 9FH. This is no ''tramping'' holiday (The Dales Centre, Grassington, North Yorkshire, is the place to contact if a walking tour is more in your line.)

It is a very exclusive affair (costing $1,100, everything included) with a maximum of 20 people for each week, every single minute packed with interest. You stay in good hotels. You travel in luxury coaches, mini-buses, and, on one occasion, on a steam train. This takes you on the North York Moors Railway built in 1830 by George Stephenson - an apt event because it was the railways in the 19th century that first opened up the beauties of the Dales to English tourists: the fact that it is a steam train is an additional bonus filled with nostagia.

But history extends backward in Northern Yorkshire much further than the 19th century. This is countryside settled centuries ago. There is still evidence of the waves of conquering Angles, Danes, and Norsemen who lived and farmed here, and not only in the rhythmic, evocative place-names. Some of the villages and small towns you will visit, Middleham and Helmsley, for example, are filled with history, and the great city of York with its ''incomparable Minster'' is a treasure house of the past. York is where you will spend the first three nights of the tour.

For the second half of the visit your base will be a comfortable hotel with an old-world atmosphere in Grassington, the Wilson Arms. It is from here that you will see the Dales proper. Some of the gray stone villages, huddling in folds and hollows as if they've grown naturally out of the landscape, seem to have remained unchanged since the 17th century. It is an area where the land is a continual rise and fall. Over the top of high moors you come suddenly on wide dales dotted with old stone barns, perfectly placed.

Drystone walls are everywhere: The Yorkshire landscape without these man-made lines of stone, sometimes climbing straight up the most inaccessible hillsides, would be unthinkable: They too stretch back deeply into the past. There are marvelous churches and abbey ruins to be seen. The tour picks up on Rievaulx Abbey in particular, sheltered by steep hills, founded by the Cistercian monks in 1132; again Herriot is at a loss for superlatives. He even rates it higher than Fountains Abbey, which is in a different part of the country.

Terry Parker, the tour's Dales expert, will be on hand as you explore the Dales. He points out the way the field patterns have developed, and gestures in the direction of one of the remotest houses in Yorkshire, high up by the source of the River Wharfe. He explains farming practices, ancient and modern. He tells you that the sheep you are watching wandering over the springy turf and heather on the high ground are called ''Swaledales'' but pronounced ''Swardles''by the local farmers.

He warns you not to stand too close to the holes in the lime rock just by the roadside on Buttertubs Pass. (It is one of the highest mountain passes in England this, between Swaledale and Wensleydale, described by Herriot as ''the finest of them all.) The holes are deceptive - one drops at least a sheer hundred feet. They are naturally formed clefts, exaggerated examples of the marvelously named limestone ''clints and grikes'' which are frequent geological phenomena of the more western parts of North Yorkshire. Herriot's Yorkshire, however, is mainly in the center and eastern parts of England's largest county.

It is not only the thrilling countryside and ancient towns and villages that the tour introduces you to: There are also people to meet. Herriot fans will enormously enjoy an ''informal''evening spent meeting Brian Sinclair. He is the real Tristan Farnon of the books. James Herriot himself has chosen to keep firmly out of sight, but Mr. Sinclair's days as his partner have provided him with a fund of good stories. Maj. and Mrs. Peter Bell, also friends of Herriot (Major Bell is the present Squire of Thirsk) treat you to lunch on the second day of the tour. Last season, the organizers found it difficult to tear participants away from here.

The same problem occurred on the fifth day when a private lunch is given by the Earl Peel of Gunnerside and his wife, Countess Peel. He is one of the organizers of the tour, incidentally. This lunch is undoubtedly one of its highlights. The Earl and his family have lived in Gunnerside Lodge, high up in Swaledale, commanding a breathtaking view down the dale, since 1969. ''Willy,'' as Terry Parker persistently calls him, seemed to my wife and me to be an unexpectedly young member of the House of Lords. He is the pleasantest of hosts and the lunch is excellent (including, when we went, my first experience of Blue Brie cheese.) Conversation may well include cricket while the two Peel children, Ashton and Iona, cavort happily around the place.

You will keep coming upon reminders of the Herriot books, and of the television series and films based on them. The ''watersplash'' at Arkengarthdale is near Gunnerside Lodge: this dramatic ford is featured at the start of each TV episode, with James and Siegfried laughing together in their car as they drive through the water rushing over the road. The house in which James lived and worked is called in the books ''Skeldale House,'' and several different houses in various corners of Yorkshire have been used to represent it in the film versions: You will see Askrigg's ''Skeldale House.'' Askrigg village is utterly picturesque with its winding street and close-knit groups of gray stone houses, cobbled market place, and 13th-century church.

A different side of the district, also much loved by Herriot, can be found in the remains of the lead mines, now mellowed by nature. It was once a flourishing industry here, until killed by foreign competition. The lead mine you will be shown is near Gunnerside. ''Gunnerside,'' by the way, is an instance of a Norse name - Gunner being a Viking chief who kept his livestock here centuries ago.

One really feels that the organizers of this tour have gone out of their way to please. I have mentioned only a smattering of what they have crowded into the schedule. ''Captain Cook Country,'' the places where the great explorer was brought up and worked before he went to sea, are given a passing look too: you see the fishing harbor at Whitby and have a picnic lunch at Sandsend. The widespread countryside of Farndale, the picture-postcard village of Hutton-le-Hole, Lastingham's church and unique, ancient crypt, are all included.

Undoubtedly, there are opportunities for walking rather than sitting - a shopping trip in York, a stroll by Lake Semerwater, one of the few, and small, stretches of water in the area. And you'll visit one of the most graceful waterfalls you can imagine, at Aysggarth. You might meet a fisherman at the coast, or a gamekeeper on the moors. Definitely you will watch a farmer herding sheep with his dog.

Of course, a week is impossibly short. Some people choose to stay on and explore the region further by themselves. There is no time on the tour to take in the glorious town of Richmond with its wynds and alleys and its castle and its Norman church and its perfectly restored little Georgian theater, and although the pretty village of Coxwold is rushed through, the Laurence Sterne Museum here has to await a later visit. This humorist and wit, author of ''Tristram Shandy,'' was a vicar in Coxwold for seven years.

One thing is certain (speaking as a Yorkshireman) and that is that the tour will leave you with a taste for Yorkshire. You can't fail to want to return. You will have caught marvelous glimpses of the beauty and variety this county has to offer the sightseer, and your own autographed copy of James Herriot's book, with its enticing photographs by Derry Brabbs, which is one of the bonuses of the tour, will remind you achingly of these glimpses and indicate how much there is still to see.