Jim Dowd:

"The tube system in south London, and certainly in south-east London, has been a joke for many years—largely because it does not exist. In the latter days of the 19th century, the system was run by a cartel. The Southern Electric Company and the Metropolitan Railway, as they then were, decided that they would not encroach on each other's territory, which is one reason why the tube system never came very far south of the Thames. Elaborate hoaxes were devised. Reference was made to saturated sand that made tunnelling impossible, and God knows what else, but it was the commercial interests of the railway companies that largely dictated the layout of the London underground as it exists today. Fortunately, in more enlightened times we have adopted a more progressive view of improving transport in and around the capital."