The London congestion charging scheme was introduced in 2003 alongside a series of other changes to the transport system, most notably improved bus services. Research on the effects of the scheme usually attributes (often implicitly) all the changes that took place in central London since 2003 to the congestion charging, while the effects of other factors, as well as the effects of trends over time, are not usually (explicitly) considered. This paper revisits the results of the London scheme to examine to what degree observed effects (related to congestion and traffic levels, changes in travel behaviour and air pollution) can be fully or partly attributed to congestion charging. Attention is also given to the amount of revenues the scheme generated. While there is no dispute over the theoretical rationale for introducing congestion charging, the London scheme reveals that questions can be raised with regard to its practical effectiveness.