19.—The Permanent Defence Force shall consist of—

(a) persons who are appointed thereto as officers and are for the time being officers of the Permanent Defence Force,

(b) persons who are enlisted therein as men under F22[section 53, 53A or 54] and are for the time being men of the Permanent Defence Force,

(c) persons who, having enlisted therein as men under section 53 and having been transferred to the Reserve Defence Force under section 70, re-enter the Permanent Defence Force under subsection (3) of section 63 and are for the time being men of the Permanent Defence Force, and

(d) persons who are for the time being members of the Army Nursing Service.