21.—(1) The competent authority may, by notice in writing, refuse to modify a certificate or licence if satisfied that the applicant—
(a)has failed to meet the conditions in regulation 8 or 16 (as the case may be) in respect of the modification; or
(b)is not a fit and proper person to hold a certificate or licence, as modified.
(2) The notice must—
(a)give reasons for the refusal; and
(b)give details of the right of appeal against the decision.