Dr Tonks is the managing director at Haven Clinical Psychology Practice. He is registered as a Practitioner Clinical Psychologist with the Health Care Professions Council. He is a British Psychological Society Chartered Psychologist, and is listed on the Society's Division of Neuropsychology Specialist Register, in recognition of his skills and training in Paediatric Neuropsychology (QiCN- Paediatric). In addition to a Doctorate in Clinical Psychology, Dr Tonks holds a Ph.D from the University of Exeter in the field of Paediatric Neuropsychology. He holds a B.Sc with first class honours and a B.A (Ed) (Hons). He is also a qualified primary school teacher with 15 years experience in the classroom.

He was previously Clinical Lead/ Mental Capacity Lead and Clinical Psychologist for a large UK charity providing support for children, young people and adults with neuro-disabilities and complex needs. He has also worked in the NHS as a Principal Clinical Psychologist practicing in adult Complex Care and Community Neuropsychology and as a Psychologist in Paediatric Neuropsychology, Paediatrics and Child and Adolescent Mental Health. He is Honorary Lecturer at the University of Exeter Medical School, Visiting Fellow: Clinical Psychologist in Paediatric Neuropsychology & Neuroscience at the University of Lincoln and is a Research Collaborator with the School of Clinical Sciences at the University of Bristol. He has been an invited lecturer for undergraduate and Masters courses, and the Doctorate in Clinical Psychology programme at the University of Exeter. He has examined Clinical Psychology research doctorates, Masters students and undergraduates and has been external examiner for universities such as the University of East Anglia, UK and the University of Tasmania, Australia.

He has particular expertise in working with children who have sustained a brain injury and has developed specialist expertise in the assessment of neuro-cognitive and socio-emotional functions in children and adolescents. He has published his research in this area extensively. He is recognised as leading authority on the subject of neuro-developmental assessment of socio-emotional behaviour, having presented research at various international conferences around the world since 2004. He has pioneered various neuro-rehabilitation intervention techniques with children, young people and adults, and provides medico-legal treatment, but also provides clinical consultancy and treatment planning in complex cases. This is particularly in cases where expert witnesses have highlighted the need for structured multidisciplinary intervention plans, systems for tracking and progress and highly specialised analysis of data.