The scale and impact of mental illness across society is huge. One in ten children, and one in four adults (approx. 15 million people) experience mental illness each year, affecting their wellbeing, relationships, and potential ability to work. The economic and social cost has been estimated as £105bn a year in England alone. New treatments are needed urgently. However, the lack of novel drug targets combined with the challenge of validating them pre-clinically, and the high failure rate in clinical trials have led to a reduced investment in drug discovery and development in the last decade and there have been no new effective types of treatment for over 30 years.