Good on ya for trying Gyp, agree totally, it's just not worth your time, effort, possibly hours spent subduing/ restraining the individual!!!! Because the Polis can't be arsed, or aren't able to come in a timely manner.
I was punched in the face on Nottingham train station, over 30 years ago, no reason, I took the lad to the floor and was comfortably pinning him down, asked a station bod to call the plod please, he just ignored me walked away, passers by did likewise...In the end I told him I was going to let him up, let him go provided he would behave...We ended up going down the road for a pint on him AND he apologised, gave me 20 quid for tearing my T shirt...He'd thought I was staring at him on the train and wanted some... a bit paranoid cos of drugs.