Hi! I need a train from London Liverpool street sometime after 19:30, please.
That should be no problem! What day are you traveling?
I would like to go this Saturday to Cambridge. 
TR2361 will be departing london liverpool street Saturday at 21:39, there is also one an hour earlier. Would you like to book a ticket for one?
I'll take the 21:39, I'll need 7 tickets please.
Alright, your tickets have been booked and the reference number is ZI1RMKW7. Is there anything else I can do for you?
You have been very helpful. Thank you. Goodbye.
Thank you very much and have a nice day!