Table 1.

Characteristics of participating prisons

Prison	Geographic area	Gender of inmates	Typical duration of stay	Category*	Capacity
HMP Durham	Local	Male	Short	B	919
HMP Frankland	National	Male	Long	A	720
HMP YOI Low Newton	Local	Female	Short	A	396

* A Category A Prison is a maximum security prison, highly secured, and used mainly for high risk offenders, whose escape would be highly dangerous to the public or the police or the security of the state, no matter how unlikely that escape might be, and for whom the aim must be to make escape impossible. A Category B Prison is for prisoners for whom the very highest conditions of security are not necessary, but for whom escape must be made very difficult [15]