The organizational history of the British Labour Party is to a significant degree the story of an ongoing struggle over the ‘how’ of election manifestos, a struggle, partly driven by a broad-based agreement over the ‘why’ of manifestos. This is a struggle between a ‘parliamentary independence’ wing and a ‘grass-roots control’ wing. Because the manifesto is seen as a programme for government action, this also means that the answer to the how takes on huge importance, because controlling the how means controlling government action. This article will show the nature and extent of the disagreement between the two wings and argue that it has repeatedly damaged the Labour Party’s ability to operate effectively. In this struggle, the two opposing sides have at various times scored temporary ‘victories’. However, whichever argument ‘won’ at any given time, the long-term result was damage to the party’s ability to function properly. The article will also argue that after multiple generations of struggle, this issue is essentially still unresolved.