A research study was undertaken to examine the working practices of four bridewells in Hampshire in relation to mentally disordered offenders (MDOs) and diversion services. A consecutive sample of individuals detained in cells and not identified by the police as having a mental disorder were screened for the presence of mental disorder and their suitability for diversion. Custody and detention staff were observed and interviewed to elicit their views and working practices in relation to MDOs. The findings revealed that in bridewells with diversion schemes an average of about 7% of detained individuals had mental disorders who were suitable for diversion but were not detected by the police. In the bridewell without a diversion scheme the figure was 14%. Conversely, many individuals without a formal mental disorder were inappropriately referred to diversion schemes. The effectiveness of screening processes by custody staff was variable. Facilities in the bridewells were not suitable for containing disturbed individuals. Delays in obtaining mental health assessments caused considerable concern for police officers and prolonged the discomfort of vulnerable individuals. Further preparation and training of custody staff is needed to improve screening procedures. Reception and detention facilities for mentally disordered individuals should be reviewed and response times for approved social workers (ASWs) and psychiatrists would benefit from improvement.