The ontological proof became something of a signature argument for the British Idealist movement and this paper examines how and why that was so. Beginning with an account of Hegel's understanding of the argument, it looks at how the thesis was picked up, developed and criticized by the Cairds, Bradley, Pringle-Pattison and others. The importance of Bradley's reading in particular is stressed. Lastly, consideration is given to Collingwood's lifelong interest in the proof and it is argued that his attention is (...) best understood as a direct continuation of theirs. In view of the fact that recent commentators have tried to draw a sharp line between Collingwood's approach to metaphysics and ontology and that of his predecessors, the establishment of this connection calls for a measure of reassessment on both sides. (shrink)