There is an equally illuminating account of pacifism and of the anti-war organisations that together formed the largest mass-movement in Britain between the wars. The story is enlivened by the constant infighting between the various anti-war groups, most notably between the biggest of them, the League of Nations Union (which accepted the use of force as a last resort), and the absolute pacifists (who were forever denouncing the Union as warmongers).

Here as elsewhere in the book, intellectual history is reinforced by anecdote and gossipy detail. Overy homes in skilfully on individual case-histories, such as that of Walter Greenwood, author of the best-selling novel Love on the Dole, while much of the material he cites to illustrate his main points is refreshingly unfamiliar. There is an amusing glimpse of an improbable gala, the "Malthusian Ball" which was held at the Dorchester Hotel in 1934 to raise money for the birth control movement. The extent of public revulsion against the arms trade is rubbed in with quotations from a source which few would have predicted, a Leslie Charteris thriller in which the Saint pits his wits against a international arms racketeer called Kane Luker (Cain plus lucre, just in case you haven't got it).

The world Overy portrays was intensely political. His sympathies are wide enough to remind us that it was also one in which people were constantly hankering to get away from politics. What was pacifism, after all, but a desire to transcend the nastier kinds of political conflict? But although this may have been an honourable impulse, it did not necessarily have honourable consequences. Follow it far enough, and you ended up with Dr Barnes, the Bishop of Birmingham, urging Britain-this was in 1934 - to disarm completely and rely on "a policy of international righteousness".