Prior to June 2015, information held centrally on prisoners serving sentences for drug related offences was not sufficiently detailed to identify offences relating to cannabis as opposed to other drugs. Providing data back to 2010 could therefore only be done at disproportionate cost.
According to centrally held data, as at 30 June 2015 (latest available), there were 1,363 offenders in prison custody for cannabis related offences in England and Wales. This number includes all offenders who have had their offence categorised as a ‘drug offence’ and in which cannabis is explicitly stated in their offence description. This number does not include instances where cannabis may have been a contributing factor to the main offence committed.
These figures have been drawn from administrative IT systems which, as with any large scale recording system, are subject to possible errors with data entry and processing.