For the purposes of section 3(5)(b), an insurer knows something only if it is known to one or more of the individuals who participate on behalf of the insurer in the decision whether to take the risk, and if so on what terms (whether the individual does so as the insurer's employee or agent, as an employee of the insurer's agent or in any other capacity).
For the purposes of section 3(5)(c), an insurer ought to know something only if—
an employee or agent of the insurer knows it, and ought reasonably to have passed on the relevant information to an individual mentioned in subsection (1), or
the relevant information is held by the insurer and is readily available to an individual mentioned in subsection (1).
For the purposes of section 3(5)(d), an insurer is presumed to know—
things which are common knowledge, and
things which an insurer offering insurance of the class in question to insureds in the field of activity in question would reasonably be expected to know in the ordinary course of business.