This section applies to a political party if—
(a) it has as its main object, or one of its main objects, the promotion of parliamentary candidatures for the Parliament of the United Kingdom, or
(b) it is an affiliate of, or has as an affiliate, or has similar formal links with, a political party within paragraph (a).
Nothing in section 29(1) shall be construed as affecting any special provision for persons of one sex only in the constitution, organisation or administration of the political party.
Nothing in section 29(1) shall render unlawful an act done in order to give effect to such a special provision.