I have a travelcard zones 2-4 used on rail or London underground but wish to travel into zone 1, would I need to get an extension to go into zone 1 or just use pay as go. Does it depend on the time of day? I am confused sometimes I can use my travelcard 2-4 and go into zone 1 but other times I cannot go through the barriers. Does it depend on the time of day, before 9.30am or after 9.30am.