IN Lloyd George -- the diary of Frances Stevenson, Lloyd George's secretary, mistress and eventual wife -- it is recorded that Beatrice Webb came to call on the great man one day in 1934, and, discussing autobiography, said that she did not think it permissible to include "what so-and-so said about somebody else -- in other words gossip -- but only one's own impressions and experiences."

Beatrice Webb's Diary is certainly autobiographical in the sense that it was written for posthumous publication; and on the whole it abides by this exemplary rule. It is her personal experiences and impressions of men and events which make it so absorbing, an which rank it, in my opinion, not far below those intimate and illustrious Greville Memoirs, which so upset Queen Victoria a century ago.

This third volume, well edited by Norman and Jeanne MacKenzie, covers three stages in 20th-century English history -- the social rebellions which ended abruptly in August 1914; the First World War whose "sustained horrors" drove an originally pro-war Beatrice into a nervous breakdown; and the hopeful beginning of the postwar Reconstruction, before England as a "Land Fit For Heroes To Live In" proved to be sadly unfit for this heroic task.

When the Diary opens, in 1905, she and her husband, Sidney Webb, are already an institution. They are professional sociologists, expert in the investigation of contemporary problems, working and writing together "with the extraordinary joy of complete agreement," and Beatrice has just been appointed by her friend A.J. Balfour, the outgoing prime minister, to be a member of the Royal Commission on the Poor Law, a rare if not unique appointment for a woman in those days.

It is one of the essentials of readable autobiography that the writer should like himself; and Beatrice Webb, though sometimes a prey to self-doubt, is usually not backward in self-esteem. There is, in fact a great deal in her character for us to admire, if not always to like; she describes herself as a "somewhat vain and quick-witted woman" who cannot bear fools or ignoramuses gladly; and it is because she found not a few of these among her fellow commissioners and did not always conceal her feelings, that the chairman, Lord George Hamilton, as she jubilantly puts it, "foams at the mouth" at the very mention of her name.

The commissioners on the Poor Law had to deal with an old and dingy problem. The Poor Law, a depressing mixture of Elizabethan and Utilitarian features, seemed to regard destitution as a crime. While her fellow commissioners sought to alleviate destitution, she hoped to abolish it altogether, by breaking up the existing law and distributing its various functions among the appropriate governmental departments; and the famous Minority Report which she and Sidney wrote together is a brilliant projection of the welfare state.

DIARIES ARE apt to be multipersonal; and in this diary, besides the radical reformer, there are distinctly two other Beatrice Webbs. One is the Beatrice who was born Beatrice Potter, daughter of wealthy upper-middle-class parents -- "members of the governing class" as she writes and not ironically. Sometimes we hear the voice of this Beatrice rather too clearly, as for example in her moments of condescension towards those very lower-class individuals, H.G. Wells and his wife. "I did H.G. a bad turn," writes this barely sufferable Beatrice in 1909 "when I introduced him to the Elcho-Balfour-Desborough Set." That is, to the Smart Set of the time.

The Webbs were leading members of the Fabian Society (that group of socialist intellectual who hoped to absorb both Liberals and Conservatives by a process of gradual "permeation") and the second Beatrice reminds us that the society was an outgrowth of a highly moral entity called "The Fellowship of the New Life." Early in the diary she complains of "a great increase in sexual emotion for its own sake and not for the sake of bearing children. And that way madness lies." This note is sounded here and there throughout this volume. Even her great friend Bernard Shaw does not escape: his plays and conversations are too erotic, not to mention his relationship with Mrs. Pat Campbell. A notable sinner in this respect, David Lloyd George, is let off, however -- perhaps because his numerous escapades come under the heading of "gossip."

These two Beatrices merely flit through this volume; they do not consistently inhabit it. The real inhabitant is a woman of keen and vivid perceptions, who seems to have met almost everybody of importance in the political world. Of Lloyd George, for example, she writes that while he is a blatant intriguer who neither likes nor dislikes, bears no malice, feels no gratitude, he has "one serviceable gift," namely "executive energy." How true! He was always a galvanizing force -- in fact a greater prime minister in World War I, probably, than Churchill was in World War II.

It was Lloyd George who brought Beatrice Webb out of her neurasthenia in 1917 by appointing her a member of his Reconstruction Committee, with the task of unraveling the whole wartime tangle of government activities. "This is the kind of work," she writes, "that Sidney and I are skilled in . . . If I keep my health and mind my manners." She served on the very important Sub-Committee on the Machinery of Government, headed by her friend Lord Haldane, but the Sub-Committee's revolutionary report -- as the next volume will presumably show -- was held up until the 1930s, when its two most viable proposals -- for a ministry of justice and a ministry of supply -- were dropped by two successive cabinets, one of them containing Haldane himself.

This third volume of the Diary, an important and searching exploration of the inner politics, intrigues and personalities of the Labor-Socialist movement, written in an enviably lucid prose, ends with the general elections of 1922 and 1923, when Sidney Webb becomes a Member of Parliament for Seaham, and the first Labor Government is formed. Sidney Webb, who joined its cabinet as president of the Board of Trade, hailed this latter event as a perfect example of "the inevitability of gradualness" -- charming Fabian language, which might have been uttered by some kindly character out of Lewis Carroll or Edward Lear. Yet he must have foreseen another kind of inevitability. The government was a minority government depending for its existence on the goodwill of its opponents; and a year later, after a somewhat inglorious career, it fell from power. As for the diary, it marches triumphantly on toward that achievement which Greville, in modest language, hoped would await his Memoirs -- namely "to contribute some pages to the record of his times and the literature of his country."