(1)As soon as a fixed-term prisoner, other than a prisoner to whom section [F281243A [F282 , [F283 244ZA,F283] 244AF282] [F284 , 246AF284,F281]] [F285 , 247 or 247AF285] applies, has served the requisite custodial period[F286 for the purposes of this sectionF286] , it is the duty of the Secretary of State to release him on licence under this section.
[F287 (1ZA)Subsection (1) does not apply if—
(a)the prisoner’s case has been referred to the Board under section 244ZB, or
(b)a notice given to the prisoner under subsection (4) of that section is in force.F287]
[F288 (1A)Subsection (1) does not apply if the prisoner has been released on licence under section 246 [F289 or 248F289] and recalled under section 254 (provision for the release of such persons being made by sections 255B [F290 toF290] 255C).F288]
F291(2). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(3) [F292 For the purposes of this section F292] “the requisite custodial period” means—
(a)[F293 in relation to a prisoner serving one sentenceF293] , one-half of his sentence,
F294(b). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F294(c). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(d)F295in relation to a person serving two or more concurrent or consecutive sentences ... , the period determined under sections 263(2) and [F296264(2B) or (2E)F296] .
[F297 (4)This section is subject to paragraphs 5, 6, 8, 25 and 28 of Schedule 20B (transitional cases).F297]
574.The release provisions for all prisoners (excluding those subject to a life sentence or one of the new sentences for dangerous offenders under Chapter 5) are dealt with in this section. All prisoners must spend a “requisite custodial period” in custody before the Secretary of State is required to release them on licence. This requisite period is calculated according to the particular sentence as described in subsection (3). For all prisoners serving a sentence of twelve months or more (excluding dangerous offenders and life sentence prisoners) the Secretary of State is required to release them on licence at the halfway point of their sentence. For prisoners serving a sentence of less than twelve months, release will be at the end of the specified ‘custodial period’. For those serving a sentence of intermittent custody release will take place at the end of each custodial period as defined by section 183. These provisions are subject to the arrangements for prisoners who have been returned to custody following a period of being unlawfully at large, as provided in section 245.