Where a bill is not payable on demand the day on which it falls due is determined as follows:
(1) The bill is due and payable in all cases on the last day of the time of payment as fixed by the bill or, if that is a non-business day, on the succeeding business day:
Provided that nothing in this paragraph shall operate to prevent a bill being paid by the drawee on a Saturday (other than a Saturday that is a public holiday or to which paragraph (d) of the definition of "non-business days" in section 2 of this Act relates) or cause him to incur any liability thereby, where -
(a) the drawee is a banker, and
(b) the Saturday concerned is the last day fixed by the bill as the time of payment, and
(c) the drawee is normally open for business on a Saturday at his address given in or ascertainable from the bill,
and, accordingly, presentation and payment of such a bill on the Saturday shall be valid and shall discharge it as fully as if it had been presented and paid on the next succeeding busi
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