generate response: It doesn't matter, the first train after 19:45 works for me. I need to book it for four people, and please provide the reference number.. Intent: book_train. Slots: train-bookpeople=4, train-departure=cambridge, train-destination=birmingham new street, train-leaveat=19:45
Response: I was able to book 4 tickets on train TR7769 departing at 20:01 and arriving at 23:44. Your reference number is H6UCCIBA . Is there anything else?