Oxleas NHS Foundation Trust has run a Court Diversion Service in South East London since 1991. It provides services for people within the earlier stages of the Criminal Justice System.

This evaluation aims to combine data from across the 25-year period since the introduction of the diversion scheme. It seeks to provide a longitudinal picture to elucidate the impact of service changes during this time.

The evaluation uses data obtained from a variety of sources for four points in time: 2015/2016, 2011, 1999 and 1991. Data across domains was collated to allow longitudinal analysis.

After the initial introduction of the scheme in 1991, the total mean time on remand was noted to drop from 67.1 days to 49.5 days (P < 0.001). There were 280 referrals over 18 months in 1991, 210 per year in 1999, 190 in 2011 and 174 between April 2015 and March 2016. Violent crimes increased from 29% in 1991 to 47% in 2011. The proportion with schizophrenia decreased from 31% in 1991 to 18% in 1999, before increasing again to 25% in 2011. The use of Section 37 hospital order disposal decreased from 15% in 1991 to just 4% in 2011.

The court diversion scheme has produced significant benefits since it was introduced in 1991, despite a rise in the proportion of violent alleged offences. Changes to the service have seen decreased use of hospital orders.

The authors have not supplied their declaration of competing interest.