Where a person, having ceased to serve as a constable in order to undertake service of a description specified in the First Schedule to this Act, resumes service as a constable during any period which, by virtue of any regulations made under section one of the Police Pensions Act, 1948, as extended by section forty-three of this Act, is to be treated in his case as a period of service as a member of a police force, it shall not be necessary for him, notwithstanding anything in any enactment, to make any declaration required to be made by him on accepting office as a constable.