There is evidence that psychosocial factors other than those discussed by Swinson et al ^{Reference Swinson, Flynn, While, Roscoe, Kapur and Appleby1} affect homicide rates and it is important to know whether these disproportionately affect individuals diagnosed as mentally ill. Specifically, there is evidence that income inequality strongly influences rates of violent crime, including homicide. ^{Reference Wilkinson2} Wilkinson & Pickett have claimed that changes in inequality also influence rates of substance misuse. ^{Reference Wilkinson and Picket3} It is thus important to know whether the increase in homicide rates described by Swinson et al could be caused by those with psychiatric problems being ‘left further behind’ in terms of income and/or social status.