The constitution should be reviewed in case it requires a sole signature by Director and Secretary or if there are any other specific requirements, this would be common so it would be important to check.
Under Section 43 CA2014, The Company’s seal shall be used only by authority of its Director(s), or of a committee of its directors authorised by its directors in that behalf and any instrument to which a Company’s seal shall be affixed shall be:
(i) signed by a Director of it or by some other person appointed for the purpose by its directors or by a foregoing committee of them; and
(ii) be countersigned by the secretary or by a second (if any) director of it or by some other person appointed for the purpose by its directors or by a foregoing committee of them.
In your case the Director and signing authority for the Company Secretary should sign.