Notwithstanding section 92 of the M1Licensing (Scotland) Act 1976 (restriction on carriage of alcoholic liquor in crates on contract carriages), but subject to section 71 of this Act, if the operator of a public service vehicle which is being operated as mentioned in section 69 of this Act, either by himself or by his employee or agent permits alcohol to be carried on the vehicle, the operator and, as the case may be, the employee or agent shall be guilty of an offence and liable on summary conviction to a fine not exceeding F1level 3 on the standard scale.