Lionel Trilling's rather patronizing suggestion that C.P. Snow's novels might have been written on a dare (he imagined a cozy London club scene in which someone challenged Snow to prove that the novel wasn't dead) was far off the mark. It is true that the late Lord Snow made his mark as a scientist, university don, civil service commissioner and even politician (as minister of technology in Harold Wilson's 1964 Labor government) even as he was writing his 11-volume "Strangers and Brothers" series.

But as we learn in this affectionate memoir by his younger brother, Snow knew that he wanted to be a storyteller years before these distractions intervened. Philip Snow recalls the exact time and place: "On the first day of 1935 Charles had the idea of a series of novels, certainly four," and "the notion . . . came to him on La Canebie re in Marseilles." When Snow, returning from France, outlined the project to his brother he added, "I believe it'll make me." And so it did, although the project took many more than four volumes and 20 years longer to execute. For the tens of thousands who have found pleasure in C.P. Snow's homely but absorbing novels (and stimulus in his essays in science, politics and literary criticism), this pleasant memoir is its own justification.

But Snow's novels touch English public life of the last half century at so many recognizable points as to whet one's curiosity about their provenance. They are all, in a sense, romans a clef; and one always welcomes a skeleton key. Philip Snow obliges by revealing the living models for major characters and the origins of some of the plots. He also sketches in the personal background.

The Snow boys--originally four--were authentic Midlands provincials, born to a happy, hardworking family in Leicester. Their father, a gifted musician, made his living as a factory clerk. But his real me'tier was as organist and choirmaster at various parish churches. He was undoubtedly the only fellow of the Royal Society of Organists on the modest street where the Snows lived, among plain folk, in a Victorian semidetached house. But their niche in the finely calibrated English social scale was perhaps a bit higher, Philip Snow says, than the novels intimate.

C.P. Snow, known as Percy until his future wife began addressing him as Charles, was a schoolboy prodigy. He was an authority on the Walter Scott novels at 11, and after a night over the rule book could referee a game (hockey) he had never seen. He studied science at Leicester, went from there to Cambridge on scholarships, and distinguished himself as a talent recruiter in the World War II British science effort.

But from 1935 on, Snow was systematically incubating the "Strangers and Brothers" novels that ultimately won him worldwide eminence and considerable money, though not the Nobel Prize he coveted. (Snow would have been a better choice than some of the more exotic laureates crowned in his lifetime.)

During the Second World War, Philip Snow was an administrator in the British Fiji islands. The correspondence between the two brothers about the war, European politics and the future is included here. C.P. Snow, interestingly, thought of emigrating to America, and might have done so had Britain's war effort failed. As it was, he became quite fond of the United States and traveled and lectured here extensively, as he did in the Soviet Union.

Snow buffs will find "Stranger and Brother" a treasury of intriguing odds and ends. For instance, the plot for the college election in "The Masters" came from Mark Pattison's 19th century Oxford memoirs, not from the Cambridge election Snow witnessed just before the war. Philip Snow portrays his brother as a sort of English eccentric, fond of cats, indifferent to food . His newspaper reading at breakfast "would be interspersed with little grunts and hums, like Winnie the Pooh."

This book, within its modest limits, is pleasant reading, although it demonstrates the eccentricity of brotherly literary judgment. "The Light and The Dark," Snow's story of the brilliant schizophrenic Roy Calvert, seems to me the least convincing of the Lewis Eliot novels. But Philip Snow regards it as "probably the most underestimated," and "would recommend anyone coming to Charles's work for the first time to start with it." That counsel is best disregarded, but otherwise "Stranger and Brother" is a useful guide to a major accomplishment in old-fashioned storytelling, and to the remarkable man who achieved it.