This article discusses the interpretation and curation of the glass plate slides surviving from the First World War civilian internment camp at Knockaloe, Isle of Man, which show internees (all assigned male at birth) presenting as female in various situations. With reference to recent debates in heritage studies concerning the social agency of museums, and to the ways in which erasure of trans history is increasingly politically instrumentalized, it argues in favour of acknowledging the possibility that some internees’ female presentation was motivated by female gendered subjectivity. The article discusses the circumstances in which people who were assigned male at birth presented as female in military contexts; considers the specific issues at stake when curating the history of marginalized groups; and analyses the multiple possible motivations for the female presentation shown in the Knockaloe slides. Consequently, it advocates a polyvocal curatorial approach, which validates the slides’ trans possibility equally alongside other motivations. It concludes by arguing for a shift in the historiographical discourse of gender and military internment, including a more mindful approach to the use of gendered language.