Music therapy pedagogy remains under-researched in the United Kingdom, with much pedagogic knowledge held implicitly by experienced trainers and supervisors. Musical training requirements are further under-theorised, emphasising a ‘high degree of musicianship’ as a single criterion while leaving unclear how musical and therapeutic identities are integrated within the Music Therapist/musician. This article presents findings from interviews with five experienced UK trainers carried out in 2017–2018. Interviews were analysed from two perspectives: a thematic analysis identified trainers’ views on what ‘being a Music Therapist’ means in musical terms, while a discourse analysis helped show how trainers position music therapy in relation to musicianship more generally. Findings suggest trainers understand musicianship in music therapy as a combination of distinct musicianship characteristics, where exceptional achievement in one does not make up for lack in another. Trainers’ assessments of competence across these characteristics not only act to identify suitable candidates for training (gatekeeping) but also discursively construct the practice of music therapy itself and distinguish it from other musical practices (fence-making). The UK music therapy training context has developed rapidly since these data were collected. Nevertheless, this study gives an account of recent pedagogic thinking on musicianship which remains relevant to current music therapy training.