--- - |2 Abstract In this article, I contribute to the literature around interagency collaboration, especially between law enforcement and health care, by reconciling the previous work of Sarah Charman (2014) with the interprofessional teamwork literature. Drawing upon a semi‐structured interview‐based study with 20 custody nurses working in English police custody suites (analysed using Framework Analysis), I explore the ways they are able to achieve interagency collaboration with a particular police officer, the Desk Sergeant. I argue that nurses accomplish interagency interoperability by interacting regularly with the Desk Sergeant, anticipating their needs and limiting their own goals to those that are commensurate with the Desk Sergeant's, notably providing information and avoiding deaths in custody. Such practices are similar to the strategies of ‘Cultural Interoperability’ noted by Charman (2014); however, this study also identifies that such strategies are only available once a successful working relationship has formed between Desk Sergeant and nurse, and as a result, similarly to the findings of interprofessional teamwork studies, the success or failure of attempts to collaborate across agencies is underpinned by interpersonal relations. The paper concludes by commenting on the importance of analysing both the interpersonal and organisation levels when studying collaboration. - 'Sociology of Health &Illness, EarlyView. '