Mesothelioma is a terminal disease that is linked to asbestos exposure. Continuity is difficult for GPs, and other healthcare professionals (HCPs), to provide within the current NHS primary care system, but is highly valued by people with mesothelioma. To understand the experiences of continuity in primary care among people with mesothelioma, their close persons, and their HCPs; how they achieve this (or not); and how it affects their healthcare service use. Realist case studies of patient journeys through the healthcare system (involving longitudinal interviews with people with mesothelioma, their close persons, and HCPs; and exploration of the organisational context). Data analysis allowed understanding of hidden mechanisms (resources and reasoning), triggered in certain contexts, leading to specific outcomes. Forty-eight interviews (involving 9 patients, 8 close persons, and 12 HCPs) were undertaken (totalling 30.8 hours/1848 minutes). Context-Mechanism-Outcome configurations related to: challenges unique to mesothelioma; capacity of patients/close persons/HCPs to facilitate continuity; multidisciplinary (MDT) approach differs from the family doctor model; and 'the NHS primary care system is broken'. Patients perceive their continuity needs to be unmet by the inflexible primary care system, which needs to adapt to a society in which people receive increasingly novel treatments and live longer with complex healthcare needs. A societal perspective shift is required to understand that an MDT now shares responsibility for care, rather than an individual family doctor. Policy documents continue to focus on access, and still do not advocate strongly enough for continuity, despite unequivocal evidence demonstrating its worth.