Having now checked PNLD myself - I am still of the opinion that the Army Act does not apply in this case as:
The Army Act 1955 and the Air Force Act 1955 contain parallel provisions with respect to the relevant Force, substituting air force for army, airman for soldier and similar changes.
The Acts create offences in relation to army and air force personnel, define the jurisdiction of courts and set out procedures for the processing of deserters and absentees.