If you have an ‘off-peak’ train ticket, which usually applies to weekdays from 9:30 am to 4:00 pm and after 7:00 pm. You can typically take any train during these times as long as your ticket is with the same train operator and unless specified otherwise. Under normal circumstances, there is a train approximately every 30 minutes from Cambridge to London Kings Cross. On weekends, Saturdays, Sundays, or public holidays in the UK, all trains are considered ‘super off-peak’, meaning that you can take any train with your given train operator. The latest train from Cambridge to London is after 10:00 pm. We recommend to download the ‘Trainline’  app to instantly book and view all train schedules.