Chiltern Duo Return tickets may require you to travel at specific times of day, days of the week or on a specific route. Website journey planners can tell you when your ticket can be used - simply enter your outward and return journey times to see the trains you can travel on. If you board a train at a time when your ticket is not valid, you will be charged the difference between the fare you have paid and the cheapest valid fare for the service concerned. In some circumstances you may have to pay a penalty fare.
If the route shown on the ticket has a + or † symbol then the ticket includes the cost of travelling between certain London Stations by either London Underground, Docklands Light Railway (DLR) or Thameslink services as appropriate to the route of the journey being made. Tickets will only be accepted by London Underground and DLR on the day of validity of the ticket. Other than to change trains, a break of journey at intermediate London Underground or DLR stations is not permitted.
All tickets and travel are subject to the National Rail Conditions of Travel.