In addition to the above philosophical influences, there was a range of issues and debates which also contributed to the rise and popularity of Idealism. For example, Idealism did respond very effectively to the social issues of the time. It was a philosophy that radiated optimism at a time of extreme social dislocation and pessimism concerning the appalling social and industrial conditions of the age. It offered a philosophy and a form of sophisticated understanding of political practice that gave a much needed emphasis to social cohesiveness and to the closeness of the relation between individual and collective responsibility. Its highlighting particularly of the importance of active social citizenship subsequently became an important theme in the early twentieth-century politics of welfare. In this sense many aspects of its output became associated, in some interpretations, with the development of a new social liberalism in the period from 1906 to 1914.In the case of Bradley, at least, this seems implausible. I get the sense reading Bradley that it was the link between Mill's empiricism and Mill's liberalism that motivated Bradley to attack Mill's empiricism so thoroughly.
A point which Vincent emphasizes and which is more plausible is the internal divisions within British idealism:
By the later 1890s and early 1900s, younger members of the Idealist school began to divide up into factions. The key binary (although it is still a marked simplification) was between Absolute Idealists (Caird, Bradley and Bosanquet) and Personal Idealists (Andrew Seth Pringle Pattison, C.C.J. Webb, Hastings Rashdall, Boyce-Gibson, Henry Sturt and McTaggart). Absolute idealism, because it tried largely to characterise the totality of experience, was indicted for a multitude of crimes. It was accused of losing God in man, or man in God; dissolving things into thought; matter into spirit; abolishing all right and wrong; and truth and error. Its comprehensiveness and inclusivity was a virtue for some, but it was also the source of major problems for others. Idealist and non-Idealist critics alike were concerned largely about the idea of a unity above and beyond the individuals who comprised it, and which had a will of its own. This doctrine of the Absolute can also be found, to a degree, in Green's problematic idea of the eternal consciousness, as well as in Hegel's notion of Geist. What role God has in relation to these terms remained a divisive and unresolved issue, even among the more Absolutist-inclined thinkers. The metaphysical, moral and political danger of a diminution of the individual and subordination to a 'higher' entity was connected by some critics, such as L.T. Hobhouse, to both German militarism and the conflict of the First World War. These critics of Idealism became known as the Personal Idealists. Amongst them, though, there was -- as amongst the Absolute Idealists -- a good deal of internal diversity of opinions. The Absolute / Personalist debate is most vividly illustrated in a meeting of the Aristotelian Society in July 1918 entitled 'Do individuals possess a substantive or adjectival mode of being?'I hope that Mander's book and other scholarship on the internal history of idealism can lead to new contacts with historians of analytic philosophy who are not always ready to recognize the important internal divisions within their own movement.