Tom Bennett begins his article with a tale of a frustrating afternoon with Year 7. We've all been there. In his case, his frustration was caused by his finding a conceptual gap between how well his class wanted to do and the actual quality of their causal thinking. Bennett decided to use counterfactuals to improve their thinking. This article shows how his own thinking changed, too. He analyses why his students had struggled with the Battle of Hastings, and then shows the process by which he decided what to do about it, absorbing and adapting the ideas in the literature. The result is a discussion of how to use counterfactual diagrams and formulae, and improved student understanding of what (and Wat) caused the Peasants' Revolt.