Mancini Vs Director of Public Prosecutions

Viscount Simon, L. C "It is not all provocation that will reduce the crime of murder to manslaughter. Provocation, to have that result, must be such as temporarily deprives the person provoked of the power of self-control as the result of which he commits the unlawful act which causes death......... The test to be applied is that of the effect of the provocation on a reasonable man, as was laid down by the Court of Criminal Appeal in Rex v. Lesbini, so that an unusually excitable or pugnacious individual is not entitled to rely on provocation which would not have led an ordinary person to act as he did. In applying the text, it is of particular importance to (a) consider whether a sufficient interval has elapsed since the provocation to allow a reasonable man time to cool, and (b) to take into account the instrument with which the homicide was effected, for to retort, in the heat of passion induced by provocation, by a simple blow, is a very different thing from making use of a deadly instrument like a concealed dagger. In short, the mode of resentment must bear a reasonable relationship to the provocation if the offence is to be reduced to manslaughter"