6.—(1) Any person who is serving in the Royal Marines under a term of service for which he enlisted before the commencement of these Regulations may, at any time during the term for which he enlisted, give to his commanding officer notice in writing of his desire to be treated as if he had entered for a term of service under regulation 3, and if his commanding officer approves, he shall from the date specified in such approval be treated in respect of his service thereafter as if he had so enlisted and not, subject to the provision of paragraph (2) below, otherwise.
(2) The right to give 18 months notice of transfer to the reserve conferred by regulation 7 may not be exercised by a person to whom paragraph (1) above applies unless he has completed by that time such a period of service as would, when added to the 18 months notice, be not less than the period to which he became committed (if any), in consideration of his being permitted to undergo a course of instruction or of receiving any other benefit or advantage, under a term of service for which he has enlisted before the commencement of these Regulations, or unless, in any other case, he has completed not less than 2 years 6 months service from the completion of his period of initial training or from the relevant date, whichever is the later.