Brief case not.
Woolmington v DPP [1935[ AC 462.
The defendant claimed that he had taken a gun with him to the house of the victim’s mother to show his estranged wife that he planned to commit suicide if she failed to return to him.
He alleged that the gun had gone off by accident, i.e. while he was showing it to her. Despite this claim the defendant was convicted of murder.
At the trial, the Judge directed the jury and suggested that the defendant had to prove it was an accident. The defendant appealed.
The House of Lords accepted the defendant’s claim that the trial judge had misdirected the jury, with it being established that the prosecution needs to prove – beyond reasonable doubt – two things. Firstly, that the defendant had actually committed the offence in question. Secondly, that he had done so with the necessary ‘guilty mind’.
(For a discussion of Woolmington v DPP see: ‘Criminal Law’ by Diana Roe - published by Hodder & Stoughton  at page 12).
See also De Costa v Optalis