Dr Spencer is Consultant Psychiatrist at Cambridgeshire and Peterborough NHS Foundation Trust and Honorary Consultant Psychiatrist at the Pain Management Centre, University College London Hospitals NHS Foundation Trust.  He qualified from the University of Cambridge, and completed his training in Cambridge and Edinburgh. He has lectured at the University of Cambridge and the University of Edinburgh, and he has practised as a Consultant Psychiatrist since 2008.  He was awarded the Donald Cohen Fellowship by the European Society of Child and Adolescent Psychiatry in 2007, the Clinician Scientist Fellowship by the MRC in 2008 and was elected to the Fellowship of the Royal College of Psychiatrists in 2016.

Dr Spencer has a particular interest in the interactions that can exist between physical and psychological conditions, particularly in chronic pain and psychological trauma. He has worked in NHS multidisciplinary pain clinics, has served as a Council Member of the Pain Section at the Royal Society of Medicine, is a Senior Fellow of the London Pain Forum, a member of the British Pain Society, the British Neuropsychiatric Association and the European Association of Psychosomatic Medicine and of its Chronic Pain Special Interest Group, and a founding member of the Functional Neurological Disorder Society. Dr Spencer has prepared CPR Part 35 compliant expert witness reports for the Court since 2012, in personal injury and clinical negligence work. He has been a co-organiser of the Cambridge Annual Medico-Legal Conference since 2014.

Since March 2020 Dr Spencer has worked as Consultant Psychiatrist at the mental health First Response Service covering Cambridgeshire and Peterborough (which he joined in the context of the COVID-19 pandemic, in order to work on the front-line in mental health during the time of crisis), where he has broad and varied clinical exposure to a range of psychiatric presentations across the lifespan.