'Advice' from City Police

no, there are many other things to consider

look at what causes most KSI's and it is driver error, so better enforcement of the laws for drivers and better prosecution with meaningful sentences would have a huge impact

more training for cyclists so they feel more confident to ride in positions that make them more visible and less likely to be pushed into less safe places on the road

there are a ton of other things that will have greater impact than bells, hi vis and helmets

This ^

But, who are you and what have you done with DJ?