In his previous novels, both for adults and for children, British writer Peter Dickinson has presented many faces: mystery writer, fantasist, historical novelist, social satirist, spinner of adventure yarns. The only thing that's been predictable about him is that each of these works is more than it seems. That is to say, Dickinson's intelligence irradiates whatever he puts his hand to and his imagination is so potent that it has seemed as if he simply could not stop himself from being original.

What is odd, then, about "A Summer in the Twenties" is that it doesn't appear to fit with what has gone before. With Dickinson, as I've implied, there are always departures, but one can make sense of them in the context of his trademark qualities, his playfulness, eccentricity and inventiveness. So, since his other books have been so quirky, it comes as a shock to find him playing it straight in this story of England between the wars.

America's familiarity with this ear, has come recently not so much from printed as from televised fiction -- Masterpiece Theatre and its ilk. Gramophone music tinkling in the background, women in clinging dresses belted low, men behind the wheels of long touring cars: This is the world into which we accompany Dickinson.

His hero, the Honourable Thomas Hankey, is just down from Oxford; the year is 1926. The youngest son of Lt. Gen. Lord Milford, C.B., D.S.O., Tom has been abruptly summond home by his father from a holiday in France. The sudden need to return doubly dismays Tom, not only because he resents being at the end of a parental leash but because he has just fallen in love. The object of his ardor, Julyan Tarrant, known as Judy, is a coquettish heiress, part flapper, part feminine enigma, whose mother is a shipping magnate.

Fears of a general strike are abroad, and Mrs. Tarrant's attitude toward the mutinous dockworkers is as intransigent as Tom's father's is to the miners on the verge of striking, although for different reasons. "I want you to learn to drive a train," the startled Tom hears his father say to him, anticipating the moment when sympathetic strikes might shut down the country's rails. But on top of this paternal call on his patriotism, there is the even less appealing assignment, couched in a way to let him know that it will earn Mrs. Trannt's favor, to ferret out the Communist agitators among the men on the docks.

The first task, though not the way he would have chosen to spend his summer, is fairly understandable to Tom. His father has told him, "I've got a bit of sympathy for the miners and not much for the owners -- after all, I know a pack of them -- but if we let the unions close the country down and keep it closed for a month, we're done for." What's more, Tom knows that, as far as his father is concerned, he is "untested" and that this is a chance to prove himself, since one of his brothers died in the war and the other, the current heir, has suffered from continous nervous collapse after the trenches.

However, his role as a spy in the class war rightly holds little attraction for Tom. A good-hearted and senstive young man, he is loyal to his kind and anxious to uphold England; at the same time, even the best of such young men can have their judgement fogged by love. So Tom reluctantly agrees to go against the public-school code of not peaching. He takes lodgings in a working-class neighborhood, makes friends all around -- especially with "Red Kate Barnes," a notorious rabble-rouser -- and keeps his ear to the ground.

What Dickinson gives us here, as we follow the adventures of Tom and Judy and Kate, of the caddish Bertie Panhard and of the mysterious Bolshie villain called "Ricardo," whose true identity remains a secret almost until the end, is sheer literary atavism. Or so it seems on the surface. But beyond the blatant nostalgia -- for a world in transition, granted, but a world, nonetheless, in which an innate English respect for order could always prevail -- is a book that uses an outmoded form to remind us of civilized values. It's Bulldog Drummond with a difference, and Dickinson is "Sapper" with a social conscience.

I don't think this is first-rate Dickinson, as remarkable and affectionate a recreation as it is. The characters play their assigned roles, yet despite some marvelous Dickinson touches they all seem a bit stagey. Like theatrical scenery, the people of "A Summer in the Twenties" appear to be painted on only one side. There is no equal of Superintendent Pibble, protagonist of six Dickinson titles and transmuted so startingly in the last, "One Foot in the Grave." Certainly none of the women here can compare to the surprising and vulnerable Lady Lydia Timms of "The Lively Dead."

But what does it mean when a master hand undertakes the working out of a corny plot populated with stock characters? One thing, for sure, is that it's a lovely, smooth read. It's the same as if Laurence Olivier undertook the title role in "Charley's Aunt" in summer rep: The audience would be transfixed. Dickinson's formidable intellect has perhaps scared away readers in the past, those who were bored by the anthropology in "The Poison Oracle" or who were confused by the alternate present in "King and Joker." There's no danger of that here: Dickinson's a special taste who has suddenly made himself very accessible.