My confidence in the police has taken a huge hit recently. My van was crashed into and the driver of the other car was caught on dashcam of a passing colleague and clearly on CCTV trying to wipe the paint transfer off. I reported it hoping to get the other persons insurance details, but the officer dealing with it hasn't even been to collect th evidence. Its been 5 weeks and I've had everything from excuses to attempts to dissuade me from pursuing it, saying it will take months and months and am I prepared to go to court and pay for court costs etc. She stopped talking when I quoted SWP road traffic reporting policy at her.
Long and short of it, you can commit a hit and run, cause over £1000 worth of damage and the police don't want to know. They actively avoid work.
I thought it was only police farces like GMP, MET and Avon and Somerset that would turn a blind eye to drug dealing and murder in order to pursue parking violations and social media transgressions.
I hope there is some justice for your friend, but without vigilante style justice, its highly unlikely.