We report on physiotherapists' acceptance of a Socially Assistive Robot (SAR) as a therapeutic aid for paediatric rehabilitation. The SAR is undergoing in situ evaluation while being deployed as part of the clinical care of paediatric rehabilitation patients at the Royal Children's Hospital in Melbourne, Australia. The robot is equipped to lead rehabilitation sessions of up to 30 minutes under the guidance of a therapist, and without technician support or Wizard-of-Oz operation. In this paper we report on quantitative and qualitative data collected from 8 therapists participating in our study across 19 rehabilitation sessions. Data were collected after each therapy session. Our results show our system achieves a high degree of acceptance, particularly with respect to its perceived usefulness, and ease-of-use. Moreover, multiple sessions operating the SAR appears to strengthen positive perceptions of our system.