(1) The judge shall
grant leave to appeal only if it is shown to his satisfaction that there is a
prima facie case justifying an appeal on one or more of the grounds specified
in section 21.
(2) An order granting
leave to appeal shall show the ground or grounds of the appeal and, subject to
section 27, the appeal shall not be heard or determined on any ground that is
not shown in the order.
(3) In determining an
application for leave to appeal the judge may inform himself in such manner as
he thinks fit.