Reformist Labour Socialism, not Marxism, won British working-class allegiance.

Evidence

But it was “Labour Socialism,” the anti-Marxist, reformist, ethical, and pragmatic resolution to the class war, that directed the policies of the British trade unions and the Labour Party, and to which British workers mostly attended: … By their very nature the rank and file—the men and women who bought and sold literature rather than wrote it, and listened to speeches rather than gave them—produced very little material of their own. We need to know more of these anonymous men and women who swelled the ranks of the trades councils, constituency parties and I.L.P. branches up and down the country. But such testimony as we do have, supplemented by the local Labour press and other historical records, testifies to the pervasive influence of Labour Socialism. — Cedric J. Robinson, Black Marxism_ The Making of the Black…, 1218