There is increasing evidence of a widespread recognition within the British trade union movement of the need to change. Amongst the directions of change being considered is adoption of the ‘organising model’ borrowed from the United States. MSF was probably the first major British union to go down this path, thereby promising to transform itself from an organisation that had pioneered the conservative ‘servicing model’ to one in the forefront of promoting a radical alternative. This transformation is far from unproblematic and this article examines the tensions and difficulties encountered through a study of NHS membership organisation two regions. In the process of the examination, the article highlights the inadequacies of approaches to union decline that either regard it as an inevitable result of objective circumstances or believe that new policies to counter decline can be adopted by managerial fiat and without recourse to widespread discussion among members to build a consensus.