Paying to use London’s roads is not a new idea. I have just come across a map showing turnpike gates (tolls) which were like the 18th Century equivalent of congestion charging. Instead of a single zone there appear to have been 16, each demanding a fee. It is unclear whether cyclists(!) and taxis were exempt from paying, or whether the tolls had any effect on reducing congestion! An interactive version can be found here. I have also included a map of the current zone for comparison.