Dr Clark is the first recipient of an award of distinction from the British Orthodontic Society for an outstanding contribution to the specialty of orthodontics. In 2008 he received an award from the International Functional Association for personal outstanding international service to functionalism and orthodontics. He has 55 years experience in orthodontic practice and is recognized as an innovator in orthodontics and dentofacial orthopaedics. In 1977 he developed Twin Blocks and the technique is now used worldwide for functional mandibular advancement in treatment of mandibular retrusion. In 2004 with Ortho Organisers he designed Invisible TransForce Orthodontics for interceptive treatment and arch development from mixed dentition to adult therapy. Dr Clark has lectured worldwide over a period of 40 years in 55 countries. Courses on 'New Horizons in Orthodontics' offer practical advice on diagnosis, treatment planning and clinical management in fixed and functional appliance therapy. A thesis "New Horizons in Orthodontics & Dentofacial Orthopaedics: Aspects of Twin Block Functional Therapy" at the University of Dundee gained the qualification "Doctor of Dental Science" after a lifetime of research in the field of orthodontics.