I need a train leaving from Cambridge.
Absolutely, what day of departure and what destination location?
I am heading to London Kings Cross and would need the train for Wednesday please. Oh and I need to leave after 18:00 sometime. 
Okay, the TR8676	train leaves at 19:00 and arrives at 19:51. Would you like to purchase tickets? 
Yes I need that for 3 people please.
I have booked your tickets. 70.8 GBP is payable at the station. The reference number is JLCUPIN6
Thanks, that's all I need. Have a nice day.
My pleasure. Thank you.