Sustainable transport policies are often reported in terms of reducing pollution, which is fair enough. Yet a recent Guardian report suggests that there may also be advantages in terms of road safety. It argues that the advent of the congestion charge greatly reduced road casualties in central London and the surrounding areas (including southern Brent, I would assume).
The same logic should apply to other measures that reduce the number of vehicles, such as the planning limits on parking spaces, the reduction in traffic from the creation of controlled parking zones and so on. This may well have contributed to Brent's success in reducing road accidents, which led to a National Transport Award back in 2011.