As a prison governor you could work in establishments ranging from high security prisons holding category A prisoners to open prisons for category D prisoners. Larger prisons can have several governors on different grades. Your duties would vary according to the size and type of prison, but are likely to include:

supervising security
making inspections
carrying out disciplinary procedures
writing reports
managing the prison budget and other resources
overseeing the development of the prison to meet government targets on, for example, inmate welfare
working with other professionals, such as medical staff and social workers