244Duty to release prisoners
(1)As soon as a fixed-term prisoner, other than a prisoner to whom section 247 applies, has served the requisite custodial period, it is the duty of the Secretary of State to release him on licence under this section.
(2)Subsection (1) is subject to section 245.
(3)In this section “the requisite custodial period” means—
(a)in relation to a person serving a sentence of imprisonment for a term of twelve months or more or any determinate sentence of detention under section 91 of the Sentencing Act, one-half of his sentence,
(b)in relation to a person serving a sentence of imprisonment for a term of less than twelve months (other than one to which an intermittent custody order relates), the custodial period within the meaning of section 181,
(c)in relation to a person serving a sentence of imprisonment to which an intermittent custody order relates, any part of the term which is not a licence period as defined by section 183(3), and
(d)in relation to a person serving two or more concurrent or consecutive sentences, the period determined under sections 263(2) and 264(2).