“Where there are two simultaneous independent events, each of which would have been sufficient to cause the damage, the ‘but for’ test produces the patently observed conclusion that neither was a cause. The only sensible solution here is to say that both caused the damage. Where the two events are separated in time, the simple answer is that the first event should be treated as the cause. This is normally the case where both events are tortuous…”
“The net result of the cases involving supervening events is that where there are successive sufficient causes of damage where both events are tortuous, cause or responsibility will be attributed to the first tort ...”