After nearly eighty years of free trade, the return to protectionism by Great Britain in 1931–2 was a dramatic event in its economic history. Interpretations of this policy reversal vary widely. For some authors it was an inevitable if perhaps belated consequence of relative economic decline. As mentioned earlier, Stephen Krasner argues that since free trade suits the strong, Britain's loss of international economic hegemony in the late nineteenth or early twentieth century demanded a change in the commercial policy regime. This does not mean the depression was insignificant in the decision. Quite the reverse, for ‘systems are initiated and ended, not as state-power theory would predict, by close assessments of the interests of the state at every given moment, but by external events – usually cataclysmic ones’, and Krasner argues that the slump provided the spur necessary to bring about a return to protection that objective assessment would long have seen as the appropriate policy regime for a second-class economic power. This longer-term perspective is consistent with the views of Forrest Capie, who has emphasised the build-up of protectionist pressures in Britain before the slump, particularly from the steel industry.

A radically different perspective is provided by Barry Eichengreen in his study Sterling and the Tariff, 1929–32. Relying heavily on the records of the Treasury and the Economic Advisory Council, Eichengreen produces a lucid study of economic thought and policy advice in the early stages of the slump.