The case focused on this hypothetical example. A customer pays for parking in a car park of the appellant (NCP) by going to the ticket machine which, on its tariff board, displays a price for one hour of £1.40 – but also states that change is not given but overpayments are accepted. She deposits £1.50 in coins into the machine, which flashes up 'press green button for ticket', which she does. The amount paid is printed on her ticket, as is the expiry time of one hour later. The customer displays the ticket in her car and leaves the car park.
In finding that the consideration received by NCP for VAT purposes was £1.50, and rejecting NCP’s submission that £0.10 was a gratuitous payment, Newey LJ stated (at para. 18):
English law, of course, generally adopts an objective approach when deciding what has been agreed in a contractual context. Here, it seems to me that, taken together, the tariff board and the statement that "overpayments" were accepted and no change given indicated, looking at matters objectively, that NCP was willing to grant an hour's parking in exchange for coins worth at least £1.40. In the hypothetical example, the precise figure was settled when the customer inserted her pound coin and 50p piece into the machine and then elected to press the green button rather than cancelling the transaction. The best analysis would seem to be that the contract was brought into being when the green button was pressed. On that basis, the pressing of the green button would represent acceptance by the customer of an offer by NCP to provide an hour's parking in return for the coins that the customer had by then paid into the machine. At all events, there is no question of the customer having any right to repayment of 10p. The contract price was £1.50.