> But at least my trips can’t be tracked. Sorry to break it to you but I'm pretty sure that unless you're actively swapping Oyster cards with random strangers,

> But at least my trips can’t be tracked. Sorry to break it to you but I'm pretty sure that unless you're actively swapping Oyster cards with random strangers, the pattern of metadata of where and when that card enters and exits the Underground or Overground, or when it takes a bus ride (and the route number at least) can soon yield a useful collection of data points (which in turn can be cross-referenced with CCTV timestamps) for any "authority" that's interested in tracking you.