There have been repeated attempts to establish mathematics qualifications for lower attaining students aged 16 years and over on vocational pathways in England. In 2004, the Tomlinson Report proposed Functional Mathematics and this paper examines the trajectory of this qualification (later Functional Skills mathematics) through analysis of policy literatures over the last twenty years and empirical data from two studies in Further Education colleges. For a time, Functional Skills mathematics flourished and was becoming valued by many stakeholders but the privileging of GCSE Mathematics in recent policy has affected its status and uptake. It is important to understand this waxing and waning trajectory if future skills policy is to have better chances of long-term success. Key challenges include the unsuccessful integration of Functional Skills with the established mathematics curriculum, the difficulty of achieving qualification recognition across the vocational-academic divide and the negative unintended consequences of linked policy decisions. Raising the adult skills base is currently a policy priority in England and understanding these challenges to a skills-based qualification that is more aligned to the needs of vocational education than to schools is important.