s 148 Effect of substituted punishment
(1) Unless it otherwise directs, any punishment substituted by the Summary Appeal Court has effect as if awarded on the day on which the original punishment was awarded, but this is subject to subsection (2). (2) Where the court substitutes a term of detention (other than a suspended sentence of service detention), the substituted term takes effect— (a) if the court makes a direction under section 189(3), in accordance with the direction; (b) otherwise, from the beginning of the day on which the punishment is substituted.