AimThis article aims to determine the extent of “personalization” and “de‐institutionalization” within the Conservative Party in Britain during the period 1940–1945 when the Party was under the leadership of Winston Churchill.Materials and methodsThe article examines the different dimensions of “personalization” and “de‐institutionalization” as defined by Harmel, Svåsand, and Mjelde in this special edition. To do so, it uses a variety of sources including: internal party records, memoirs and biographies, contemporaneous diaries, letters to party leaders, and survey research undertaken by the organization Mass Observation.ResultsThe article identified that a limited degree of personalization took place during the period. This was largely in relation to the movement away from existing internal policy and procedures, especially those to do with electioneering. Evidence regarding other dimensions was mixed with a notable lack of change in the perceptions other parties and their leaders held about the Conservative Party.ConclusionThe article suggests that the personalization that occurred within the Party was largely a product of necessity, notably the unpopularity of the Conservative “brand” during World War II, compared to Churchill's own personal popularity, as well as the disruptions caused by the war itself. The article argues that this was enabled, to an extent, by the already high degree of latitude that the Conservative Party afforded its leaders. At the same time, the article notes the way in which defeat at the 1945 general election led to the Conservative Party “snapping back” to its pre‐war highly institutionalized form. Both findings highlight the extent to which electoral calculations were central to the process of personalization and its subsequent reverse.