In the case of a person to whom article 81(1)(a), 82(1)(a) or 83(1)(a) apply who ceases to be so employed but immediately upon such cessation,

(a) becomes employed in any other of the employment mentioned in any of the said articles, the provisions of Part II shall, in relation to that person, be modified in accordance with article 81(2), 82(2) or 83(2), as the case may be, for the duration of such employment, or

(b) becomes employed as a Garda trainee or a cadet in the Permanent Defence Force and immediately after the cessation of that employment becomes employed as a member of the Garda Síochána or as an officer holding a commissioned rank in the Permanent Defence Force, as the case may be (hereafter called 'the second mentioned employment'), the provisions of Part II shall, in relation to that person, be modified in accordance with article 81(2) or 82(2), as the case may be, for the duration of that second mentioned employment.