Bolton v Stone [1951]

Plaintiff struck by cricket ball batsman
had hit out of ground. 
Such an event foreseeable; indeed balls had
to defendants knowledge been hit out of ground before.
Yet House of Lords considered likelihood of
injury to person in plaintiff’s position was so slight, bearing in mind
distance from pitch to edge of ground, presence of fence etc, that defendant was
not negligent.
Lord Reid: ‘I think that reasonable men do
in fact take into account the degree of risk and do not act upon a bare
possibility as they would if the risk were more substantial’     
Both likelihood of injury and seriousness
of injury risked are taken into account in assessing risk.
v London & St Katherine Docks Co
Erle J set out conditions for application
of principle.
(i)  Thing must
be under control of defendant or his servants.
Accident must be such as could not in the ordinary course of things have
happened without negligence.
(iii)  Absence
of any explanation by defendant.