The Registrar General may, in accordance with such terms and conditions as may be specified in the authorisation, grant to any person a temporary written authorisation to solemnise—
(a)a marriage or marriages specified in the authorisation; or
(b)marriages during such period as shall be specified in the authorisation:
Provided that the authorised person must at the date of the granting of the authorisation be 21 years of age or over.