Illegal diversification strategies in farming contexts are neglected in research terms. There are endogenous and exogenous factors that influence the potential strategic capability and activity of illegal entrepreneurs and criminal farmers. Internal factors include the personal characteristics of the farmer–qualities and skills. External factors, outside the control of the individual illegal entrepreneur, include the activities and processes undertaken by them, the characteristics of the illegal enterprise, government policies, markets and environmental factors. Using a documentary research methodology of 210 case studies, located on the internet, from across the UK (where farmers had been charged with criminal offences relating to their occupation), the article contributes to the literature on farm diversification and rural crime.