Me and my friend will be going to London this spring. I've been to London before and I know that the tube is the most convenient form of transportation. I went to London with my family six years ago (when I was 13) and I vaguely remember her going the turnstile ahead of me and then passing back her Travel Card. Is my mom a thief?! Or is it possible that we could by only one Travel Card and get by with one of us going first and then passing the card back? Thanks.