The aim of this article is to establish the critical significance and value of work which was the product of the unique creative partnership developed by Valentine Ackland and Sylvia Townsend Warner during the 1930s. During that period, I argue, they imagined more variously and more incisively together, through mutual awareness and acceptance, than they would in all likelihood have done had they never met and fallen in love. An understanding of the sharp differences in temperament, outlook and reputation which precluded full-scale collaboration freed each of them, in turn, to pursue contrasting aspects of concerns held in common. So adventurous was that pursuit, at times, that it merits comparison with recent investigations of the idea of the ‘posthuman’. Since Warner was by far the more prolific author, I have tried to balance my account of her partnership with Ackland by drawing extensively not only on published fiction and poetry, but also on diaries and letters, and on a variety of other kinds of material from the archive.