I describe the role of the scientist Dr Anne McLaren in the public and parliamentary debates on human fertilisation and embryology (HF&E) in Britain between 1982 and the resulting Act in 1990. A focus on McLaren’s contributions to these debates elucidates how the case in favour of embryo research was constructed. Drawing especially on the use of the contested term ‘pre-embryo’ by the pro-human embryo research lobby to describe the subject of experimentation, and the development of pre-implantation genetic diagnosis (PGD) over the same time span as the debates, I show how a pro-research case was built around the idea that biology could be used towards broadly shared clinical goals. I tie this evolution of a case to McLaren’s expertise, and show how McLaren combined an authoritative scientific understanding with the idea of moral purpose and social good, necessitating a language that could reflect both. I go on to draw on McLaren’s biography, showing how she cultivated a ‘style of practice’ that relied on the non-literal translation of biological information to arrive at public consensus. I engage with several areas of literature, beginning with the literature on the HF&E debates and analyses of the use of the term ‘pre-embryo’ in science and technology studies, and feminist cultural studies. I add a more detailed description of the specific biological arguments made by the pro-research lobby and show how these reflected a shifting position for the scientist in public debate. I also contribute to material-semiotic methodologies used in feminist cultural studies by scholars such as Donna Haraway, Evelyn Fox-Keller, and Susan Squier, showing how close readings of key documents can be used to extrapolate from an individual’s life to better understand the causality of a public debate. My combined archival research and interviews with McLaren’s former collaborators leads me to foreground a particular tension around the legacy of the biological model used in the debates. I show how the scientists I interviewed repeatedly distanced themselves from the relativistic biological case they helped invent in the 1980s, describing their role instead as a literalist transmission of biological facts. An analysis of the work that McLaren did, I argue, serves as a reminder of the iterative process that scientists performed in order to arrive at a clinical translation. I use the metaphor of ‘superimposition’ to explicate this process, a term used by McLaren to describe her own approach to policy-making, as well as in the writing of C. H. Waddington, who was a formative inspiration to her as a scientist. The metaphor helps to describe McLaren’s method of layering social, legal, clinical, emotional and scientific arguments in order to build consensus based on overlapping concerns, and allows me to develop McLaren’s role as a case study in broadening the conventional use of ‘translation’ in the post-millennial climate of biomedicine. I conclude that a multi-faceted understanding of the process of translation offers a productive and inclusive model for policy discussions, and one which continues to prescribe a role for scientists in the process of developing legislation in biomedicine today.