In [case], Lord Denning MR distinguished between situations where a ticket is purchased in a face-to-face transaction, (for example, at a ticket office), and situations where a ticket is purchased from a machine:
The offer is made when the proprietor of the machine holds it out as being ready to receive the money. The acceptance takes place when the customer puts his money into the slot. The terms of the offer are contained in the notice placed on or near the machine stating what is offered for the money. The customer is bound by those terms as long as they are sufficiently brought to his notice beforehand, but not otherwise. He is not bound by the terms printed on the ticket if they differ from the notice, because the ticket comes too late. The contract has already been made …