(1) Where, in any proceedings against a person for an offence under section 5, 6, 7 or 8, it is proved that -

(a) a gift, consideration or advantage has been -

(i) given to an official or a connected person of an official,

(ii) given to a person while intended to be for the benefit of an official or a connected person of an official, or

(iii) received by or on behalf of an official or a connected person of an official,

and

(b) the person who gave the gift, consideration or advantage, or on whose behalf the gift, consideration or advantage was given, had an interest in the discharge by the official of any of the functions to which this subsection applies by virtue of subsection (3),

the gift, consideration or advantage shall be presumed to have been given and received corruptly as an inducement to, or reward for, or otherwise on account of, that official doing an act in relation to the performance of any of those functions, unless the contrary is proved.