9. If in the case of any solid fuel sold otherwise than by means of a vending machine, the buyer so requests—N.I.
(a)with respect to any of that fuel the delivery of which has not at the time of the request been completed; or
(b)if the request is made before the departure from the premises at which the fuel is delivered of the person delivering it, with respect to any of that fuel the delivery of which has been completed but which is still capable of identification,
the seller shall cause the fuel to be weighed by means of suitable weighing equipment in the presence of the buyer and, in the case of any fuel such as is mentioned in sub-paragraph ( a), before the delivery of that fuel is completed; and if this paragraph is contravened, the seller shall be guilty of an offence.