6An offender who was ordered to be detained in a detention centre on a date before the commencement of section 124(1) of this Act shall, if the order has not expired at the commencement of that section, be treated for all purposes of detention, release and supervision as if he had been sentenced to detention for the like term in a young offenders institution.
7A person who at the commencement of section 124 of this Act is detained in a detention centre by virtue of a custodial order—
(a)under section 71AA of the [1955 c. 18.] Army Act 1955, section 71AA of the [1955 c. 19.] Air Force Act 1955 or section 43AA of the [1957 c. 53.] Naval Discipline Act 1957; or
(b)under paragraph 10 of Schedule 5a to the Army Act 1955, Schedule 5A to the Air Force Act 1955 or Schedule 4A to the Naval Discipline Act 1957,
shall be detained in such young offenders institution as the Secretary of State may direct, and any enactment applying to persons detained in young offenders institutions shall apply to a person so detained under this paragraph.
8Section 5 of the [1974 c. 53.] Rehabilitation of Offenders Act 1974 (rehabilitation periods) shall continue to apply as regards any person who, before the commencement of section 124(1) of this Act, had served a sentence of detention in a detention centre as if the said section 124(1) had bot been commenced.