generate response: This one will do. I will need to book for 4 people. Can I get the reference number once booked, please?. Intent: book_train. Slots: train-arriveby=14:30, train-bookpeople=4, train-day=tuesday, train-departure=ely, train-destination=cambridge, train-leaveat=05:35
Response: The booking was successful and your reference number is 2KELM023 .