Drew v Nunn 
Principle: The supervening mental incapacity of a principal has the effect of terminating the actual authority of his agent: ‘The actual authority of an agent whether conferred by deed or not and whether expressed to be irrevocable or not, is determined by the death or supervening mental incapacity of either the principal or the agent’. However, he may have continuing ostensible authority to bind the principal
Bramwell LJ expressed the view that only insanity amounting to dementia would suffice to annul the authority of an agent.
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