Child's Pass for London Underground

Go to this page, then click on the tab marked 11-15 : http://www.tfl.gov.uk/tickets/14416.aspx Then from that page there is another link to the page which explains how to get the 11-15 Oyster photocard that they need. It's here : http://www.tfl.gov.uk/tickets/14310.aspx Without an Oyster card, 7 day paper travelcards are now only available from London main line stations, not from Underground stations. If Marco is around then he will know more than me, but it looks like you can still get a child-rate 7 day paper Travelcard, you will just have to buy it from one of those main line stations (Liverpool Street, Kings Cross, Euston, Paddington, Victoria, Waterloo, London Bridge or Fenchurch Street). See this page : http://visitorshop.tfl.gov.uk/travelcards/1-day/product/day-anytime-travelcard.html

Without the 11-15 photocard your choice is restricted to child rate single cash fares or paper one day travelcards from TfL. From National Rail you could buy a 7-day paper travelcard at children's rates; this will require a photocard which you can get on the day, and proof of age.

We just did this a few weeks ago. Our 15 year old son is considered a child still which was great for the pocketbook! We simply went to a photo booth across the street from the station we were in, took it to the ticket booth in the station and got 7 day travelcards for the three of us. Ours were Oyster cards and his was a paper, machine read card that he carried in his Oyster wallet with his London Tube picture ID they made right there on the spot. It was super easy and so convenient for the solid week we were there. After that, for the shorter periods of time we were in town, we just loaded up our Oyster cards 15-20 pounds at a time at a ticket machine - we used cash for this. It is very easy to check the balance on your Oyster card at any ticket machine by just holding it up against the round yellow pad...it displays your balance on the screen. Not sure if loading them up like this was the cheapest way but it certainly was the most convenient as the lines at some of the central London tube stations for the ticket windows were sometimes very long. For our son's card we would just buy additional one-day or three-day travelcards depending on how long we were going to need it.

Great. Thanks so much for the detailed info everyone!