The career stage between PhD and lectureship, conventionally called "postdoctoral", has traditionally been seen as transitional. However, with an estimated one third of university researchers in the United Kingdom having been employed on temporary contracts for more than 10 years, the transitional nature of this career stage is questionable. Despite so many research staff being in long-term employment on short-term contracts, the lack of visibility of this population, which does not have a legitimate place within the current academic career structure, means that we do not know how deliberate or accidental their career choices are. Based on semi-structured interviews with long-term researchers (LTRS) at one university in the United Kingdom, this is the first study to investigate the personal and professional circumstances behind the career path of long-term researchers on temporary contracts. Three categories of LTRS were identified: 1) the candidate, who wants to follow the traditional academic career pathway and to secure a lectureship 2) the accidental long-term researcher, who did not or could not plan their career path 3) the career researcher, who sustains a research-only career despite the precarity of such positions. Most participants had belonged successively to two categories. Some obstacles to career progression transcended the categories: inequal access to opportunities for developing one's teaching portfolio, poor or lack of managerial support, the perceived prestige or lack thereof of one's field, and bullying and discrimination. We argue that short-termism and lack of visibility play down considerably the contribution of long-term researchers to the financial and academic success of research institutions. We also argue that traditional-but still in place-structures in academia are ill adapted to the contemporary demographics and practices of the research community; we recommend that future studies involve HE sector stakeholders to review and to reform the academic career structure.