The Labour Party saw collective security as war prevention, not alliance building

Evidence

T. D. Burridge suggested one reason for the Labour Party’s new vitality: “Though the Party never officially adopted an outright pacifist position, a dedicated pacifist, George Lansbury, was Leader of the Party from 1932–35. In addition, Socialist theory interpreted war in economic terms as a clash of rival imperialisms—the last, most decadent stage of capitalism. Even towards the end of the turbulent 1930s, the Party’s advocacy of the collective security doctrine owed relatively little to the idea that the possession of allies would be the best means of fighting a war. Instead, much greater emphasis was placed on the argument that a collective security policy would be the most effective way of preventing a major war.” — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 2410