PAUL THEROUX, one of the most diligently prolific of American writers, has some 10 books behind him fully popular book of travel, The Great Railway Bazaar, and his last novel, The Family Arsenal, which was well received when it appeared last year. All this I hasten to add, and Theroux is several years short of 40. Imagine.

In his industriousness, as in a number of other particulars, Theroux, who was born in Massachusetts, seems more English than American. He is dedicated to the craft of writing in a way that few Americans are.And his work shows the sort of careful, steady improvement that can be seen in a John Wain, or even an Anthony Burgess. Since Saint Jack, Theroux has deserved our attention as a novelist. With the success of The Family Arsenal he now has it.

That being the case, it is interesting and again characteristic of the English mode of authorship he has adopted as his own that he should follow up his big book with a modest one like The Consul's file. It keeps his hand in, keeps his name before the public, and a book of such obvious quality as this may even win a few new readers for him. By contrast, most American writers, because they tend to be more ambitious and competitve, would have chosen to go into retreat on a Guggenheim and top that last success with an even greater one. More of them than would admit it are still trying to write the Great American Novel. Clearly, Paul Theroux is not.

The Consul's File, in fact, is not even quite a novel - nor is it a book of short stories, though nearby all the pieces in it have appeared separately in various magazines over the past few years. It is a collection of stories and sketches related in setting - all take place in or around a backwater of Malaysia which Theroux calls Ayer Hitam - and by their point-of-view, that of the young, unnamed American consul there.

It is very much the consul's book. Althouh a bit shadowy, and barely more than a voice in some of the books "chapters," he gradually materializes as a fundamentally decent sort, an inhibied bachelor making his way as best he can through the maze of social contacts and modest professional duties that constitute the day-to-day reality of consular life. If there is a foreign serve type, then surely he conforms to it. The best of the stories - "Dependent Wife," "Pretend I'm Not Here," "Dengue Fever," "Diplomatic Relations" and a few others - are those that involve the consul most directly. It is a [WORDS ILLEGIBLE] of Paul Theroux's success here that we finish The Consul's File wanting to know more about the Consul, wishing the book were a little longer than it is.

Without being very lone on local color The Consul's File manages to convey a great deal of the spirit of its particular place. Theroux does it through his characters, mostly - the English hanges on from colonial days, the Malaysian melange of Oriental race the Americans, who, for whatever reason, are just passing through. Theroux is a rathert austere stylist who [WORDS ILLEGIBLE] with the economy of a real short story writer, concentrating not on lish passages of description but rather on bits and pieces of incident: "Stories have no beginning or end; they are continuous and ragged" - and on the people involved in them: "I have never believed that characters in fiction vanish after the last page is turned - they have other lives, not explicit or remarkable enough for fiction and yet it would be sad to think they were irrecoverable."

These quotations are taken from the last piece in that book. "Dear William," one that surey was written specifically for the collection. With its references to people and happenings in other stories, it only makes sense as a kind of summary of the rest, a last word to the reader, an envoy. In it, Theroux speaks more personally than he ever has before the writing of fiction: "I've always been rather amused by novelists who write autobiographically the credulous self promotion, the limited vision, the display of style. Other people's lives are so much more interesting than one's own."

In this; he lines up solidy with the English. Theroux has thrown in his lot with the Graham Greeres and the Somerset Maughams (Where shadows looms especially large over the stories in The Consul's File) against the Norman Mailers and the Philn Roths. The choice is the right one for him.It suits his temper well.