I don't have costs for London to hand, but a FoI request was made to Nottingham Police, who state the cost of training a police officer is £12,900, and the average payroll cost of an officer is £30,520*
So, that £1.23M could have paid for 95 officers to be trained, or could have funded 40 man-years of policing in the borough.
We don't even need fully qualified police officers on the street. PCSOs would do the job. PCSOs (£2,100 training, £28,817 payroll) out on the streets, observing dangerous driving as high-credibility witnesses. Fast-tracking prosecution.
*needs to be adjusted for London weighting
Just one PCSO rotating around accident blackspots with a camera would be a serious deterrent to all sorts of dangerous driving.