LEN DEIGHTON published Berlin Game in 1983, followed it up with Mexico Set and now comes forward with London Match. The analogy with tennis is sketchy, since a good many games have to be played to win a set and several sets to win a match. But we are, I suppose, meant to conclude that by the end of the present volume there has been a decisive climax to a long and complex action, and that one player or side has gained a victory. The characters, however, turn out to have little sense of this. "It's not game, set, and match to anyone," the protagonist says on the final page. "It never is."

Is this perhaps a neat way of hinting that there may be more to come about Bernard Samson of London Central, his wife Fiona -- whose sheer inconceivability establishes once and for all the robust character of Mr. Deighton's imagination -- and a prodigal array of men and women nearly all of whom have some connection with espionage? If this be so, the writer is well entitled to his reluctance to have done with them and their environments in London, Mexico City, West and East Berlin. The characters, although liable to bore a little during their frequently over-extended verbal fencings, are tenaciously true to themselves even if not quite to human nature. Ben Jonson himself would have approved of them. The places, whether urban or rural, can be described only as triumphs alike of painstaking observation and striking descriptive power. This is particularly true of Berlin: as, for example, the edge of the Tiergarten with its abandoned embassy buildings "like the gigantic hulks of a rusting battlefleet."

Sometimes, indeed, Mr. Deighton's linguistic resourcefulness is at odds with vraisemblance, but this happens less frequently than in the earlier books. In Mexico Set, for example, we come on somebody with "a hard unyielding face, smooth like a carefully carved netsuke handled by generations of collectors, and darkening as elephant tusk darkens when locked away and deprived of light." It seems not probable that this elegant fancy should come to Samson when it does.

But other secret agents too are keen philologists:

"'These airline blighters speak their own language,' said Dicky. 'Have you noticed that? Stewardesses are hostesses . . . safety belts are lap straps, and emergency exists are safety exists. Who thought up all that double-talk?'

"'It must have been the same PR man who renamed the War Office the Ministry of Defense.'"

With what he thinks of as an English upper crust Mr. Deighton is linguistically less assured. Thus a woman called Daphne has, we are told, the loud voice and upper-class accent that go with weekends in large unheated country houses, where everyone talks about horses and reads Dick Francis paperbacks. This is fair enough, down even to Dick Francis. But then Daphne suddenly says, "I'm sorry we can't go into the lounge." In England (as Mr. Deighton, who is London born, ought to know) only quite shockingly vulgar and plebeian people call a drawing-room or living-room a lounge. Lounges are located in hotels or at airports. Daphne has let Mr. Deighton down.

London Match is full of this class stuff, which is conceived of largely in terms of expensive dressing and eating and drinking, with plenty of authentic brand names thrown in. We learn just what claret or champagne is being poured, and the "public-school mafia" at London Central goes to Savile Row for its tailoring almost to a man. This general expensiveness, although irritating and often seemingly no more than inconsequent padding, is by no means without its function in the total picture. It all come to us from Bernard Samson on a note of ready compliance masking alienation, and we thus feel him to be what a secret agent should essentially be: a loner in disguise.

But what is this book -- what are these books -- about? The answer, if it has to be given in a word, is treachery. There is scarcely a character whose main concern is not with the danger of betrayal of one sort or another. Neither British intelligence nor the KGB ever seem to deliver anything of any consequence. Is such-and-such a man or woman a double agent, or susceptible of being "turned"? If apparently successfully "turned," is the success illusory and the agent's true allegiance still where it began? In Berlin Game, indeed, there is somebody in East Berlin who has been transmitting to England specific information in the field of economics and finance. But in general the rival secret services are concerned only with their rivalry. At one point we are, rather surprisingly, taken on an extended tour of the interior of 10 Downing Street. But although we are told that the prime minister dislikes smoking, neither she nor any other minister of the crown is shown as taking the slightest interest in the goings on at London Central. And at London Central, there is another and wholly interiorized network of suspicions and treacheries. Everybody -- to express the thing loosely -- is after everybody else's job. Almost everybody, moreover, is after -- or suspected of being after -- everybody else's husband or wife. The spectacle is not without a certain power to entertain. But, like Restoration Comedy, it is a purely speculative scene of things.

Closing these undoubtedly diverting books, I am reminded of what Sainte-Beuve had to say to Flaubert after reading Salammbo: "If you want to interest us, depict for us people who are similar or analogous to ourselves. Look well and you will find some, even down yonder." By J.I.M. Stewart; J.I.M. Stewart is the author of "Eight Modern Writers" and of "A Staircase in Surrey." As Michael Innes he has written many detective novels featuring Inspector John Appleby.