Oxford could do with one. (Yes, it has Gloucester Green, but that is only used for long-distance services and a small selection of mainly medium-distance routes going to places west of the city). Otherwise it can be as much as a 10-minute walk (perhaps even more) between the stops at which (e.g.) buses from places northerly arrive and those to which buses to points southerly depart. And, while there are a fair number of posters on bus stops explaining this, it's far from user-friendly. As with so many other infrastructural failings of Oxford, the history and geography conspire to prevent anything very much being done about this....