What is the test for express malice in a defamation case?

15 He referred extensively to Horrocks v. Lowe, [1975] A.C. 135 and at pp.60 and 61 of his judgment quotes from that case: 'Express malice' is the term of art descriptive of such a motive. Broadly speaking, it means malice in the popular sense of a desire to injure the person who is defamed and this is generally the motive which the plaintiff sets out to prove. But to destroy the privilege the desire to injure must be the dominant motive for the defamatory publication; knowledge that it will have that effect is not enough if the defendant is nevertheless acting in accordance with a sense of duty or in bona fide protection of his own legitimate interests.