However, in relation to the issue of causation, Popplewell J adopted a cautious approach. Referring to the
50/50 contribution clause in both policies, he stated that the clause would be applicable if: "(a) there was
such certainty that it is not possible to reach any conclusion as to when the damage occurred; or (b) one
theory is so improbable that even if the other theory is ruled out, it cannot as a matter of common sense
be described as more likely than not to have occurred".