On his return to England in 1905, Milner joined in two major, and to his mind interrelated, political and imperial struggles both amplified by the threatening international climate of the post-Boer War era. The first was the fiscal battle royal between Joseph Chamberlain's social imperialist Tariff Reform movement and the deeply entrenched Free Trade orthodoxy, an article of economic faith to many in both parties, but a particular Liberal shibboleth. Milner had been one of the first to be initiated into the mysteries of Chamberlain's scheme to link up the Empire by imperial preference two years before in South Africa. The second crusade was the campaign for national service and preparedness led by Lord Roberts. This was at loggerheads with England's long standing voluntary tradition, its prejudice against large standing armies, and its reliance on the navy with its hallowed place in the British psyche.

Balfour cut considerable ground from under the movement for national service with a Commons declaration in May 1905 that invasion (with France the likely foe) was ‘not an eventuality which we need seriously consider’. At the same time, Chamberlain seemed to be retreating from any bold social reform policy to counter the inroads made by the opposition. Milner's former South African compatriot Fabian Ware, who had returned to England and become editor of the conservative Morning Post, wrote to him, ‘we want you to come and lead us to put this country straight. “We” is a large majority of the people who only want leading to do one of the biggest things this country has seen.’ The ‘inevitable question’ from both the supporters of Tariff Reform and universal service who knew Ware had served him was ‘“Tell me about Lord Milner, is he the man we want?”’ All these people, Ware reported, had ‘backed Joe for all they were worth now they are holding back their money feeling uneasy owing to the obvious mistakes they see he has made in details’.