This book has argued that the British Left's reaction to the First World War was characterised by support for Britain during the conflict, and that this patriotism was by no means incompatible with their leftist beliefs. Further, this support for the war effort was instrumental to the growth in support for Labour, the statist development of the labour movement after the war, and the enhanced cohesion of the Left after 1918. In Chapter 1, there is little to challenge Douglas Newton's argument that the commitment of the British Left to internationalism before 1914 was rather artificial. Further, while the chapter did not take issue with most of the arguments outlined in Paul Ward's Red Flag and Union Jack, perhaps Ward underestimated the extent to which socialism and patriotism sat together. To quote from Stefan Berger's review, Ward's book is ‘still informed by a clear sense of binary opposition between the two concepts’. Chapter 1 aimed to show how the Red Flag and the Union Jack could be one and the same banner. It argued that the events of August 1914 did not represent a great turning point for the Left, but rather demonstrated continuity with pre-war values. Nonetheless, there was an easing of some of the various contradictions of the Left's attitude towards nationalism in this period. No longer did they have to espouse pacifistic internationalism whilst campaigning for the voters of a working class that did not share these instincts; in the climate of 1914–18 they could be unapologetically patriotic, and use that patriotism to indict the government.

Chapter 2 argued that, far from being a minority strand, labour patriotism – whilst equivocal and conditional – defined the Left's response to the First World War. Though most on the Left looked to prevent the coming conflict in the final days of July and early August, after war was declared most promptly reversed their position. John Horne was correct to write of the ‘choice of 1914’ – the belief that Britain, however imperfect, was preferable to Germany – but he understated the extent to which this choice was forced upon labour elites by a patriotic working class. Scholarship that has sought to downplay left-wing commitment to the war effort, such as Catriona Pennell's A Kingdom United, simply cannot be sustained by the evidence of labour patriotism at both elite and subaltern levels.