4. (a) It is unlikely that you are right. Of the various defences that exist, none of them seem to be available to B on the known facts.

It is a defence to prove that the plaintiff consented to the publication of the statement, or that it was an honest opinion based on reasonable evidence.

It is also a defence for the defendant to show the statement was true (known as the defence of ‘justification’) or that its publication was in the public interest.

Another defence, absolute privilege, applies only to statements by members of parliament in the house, and to judges, barristers and witnesses in court proceedings. Another lesser, qualified, privilege may apply if a person made the statement in their official capacity to someone who had an interest in receiving it, such as communications between government officials or in an employment context, provided that in the circumstances the statement was reasonably made.

Of course, if additional facts were known, the answer might be different.