(1)In determining for the purposes of this Chapter or Chapter 3 (prison sentences of less than twelve months) whether a person to whom a direction under section 240 relates—
(a)has served, or would (but for his release) have served, a particular proportion of his sentence, or
(b)has served a particular period,
the number of days specified in the direction are to be treated as having been served by him as part of that sentence or period.
(2)In determining for the purposes of section 183 (intermittent custody) whether any part of a sentence to which an intermittent custody order relates is a licence period, the number of custodial days, as defined by subsection (3) of that section, is to be taken to be reduced by the number of days specified in a direction under section 240.