If, after the date on which an agreement referred to in section 21(1)(b)(i) is signed by the employer and the employee (whether or not the approved remote working arrangement to which it relates has commenced), the employer and the employee so agree, in writing -

(a) the remote working arrangement may be postponed to such time as may be agreed to,

(b) the period of the remote working arrangement, if any, may be curtailed in such manner and to such extent as may be agreed to, or

(c) the form of the remote working arrangement may be varied in such manner as may be agreed to,

and in such a case the agreement referred to in section 21(1)(b)(i) shall be deemed to be amended accordingly.