(1) It shall be a defence (to be known, and in this section referred to, as the "defence of honest opinion") to a defamation action for the defendant to prove that, in the case of a statement consisting of an opinion, the opinion was honestly held.

(2) Subject to subsection (3), an opinion is honestly held, for the purposes of this section, if -

(a) at the time of the publication of the statement, the defendant believed in the truth of the opinion or, where the defendant is not the author of the opinion, believed that the author believed it to be true,

(b)

(i) the opinion was based on allegations of fact -

(I) specified in the statement containing the opinion, or

(II) referred to in that statement, that were known, or might reasonably be expected to have been known, by the persons to whom the statement was published,

or

(ii) the opinion was based on allegations of fact to which -

(I) the defence of absolute privilege, or

(II) the defence of qualified privilege,