Beyond the M25: What’s the Furthest a London Bus Gets from London?: A Complete Guide By merely using your Oyster Card to ride one of London's red buses, a silent agreement is made. This agreement is quite straightforward, as it assumes the bus will remain within the confines of the expansive city, travelling through its congestion charging areas and suburban roundabouts, and even passing famous monuments. But there's an unknown aspect of London's bus system, controlled by Tra