Little is known about the evolution of electoral sentiment over British election cycles. How does party support converge on the eventual election outcome? Do preferences evolve in a patterned and understandable way? What role does the official election campaign period play? In this article, we begin to address these issues. We outline an empirical analysis relating poll results over the course of the election cycle and the final vote for the three main political parties. Then we examine the relationship relying on vote intention polls for the seventeen British general elections between 1950 and 2010. Predictably, polls become increasingly informative about the vote over the election cycle. More surprisingly, early polls contain substantial information about the final outcome, much more than we see in presidential and congressional elections in the US. The final outcome in Britain comes into focus over the long campaign and is to a large extent in place well before the official election campaign begins. The findings are understandable, we think, but raise other questions, which we begin to consider in a concluding section.