There are dickhead fans, there are dickhead police.
If the minority of fans act up, these days they are recorded and usually at a later date brought before a court and dealt with.
When a minority of coppers act up, what happens? There is no excuse whatsoever to not be wearing his number, other than deliberately, knowing he is going to get a bit handy if the opportunity arises.
The man in question won his appeal, and the police and prosecution don't want to reveal why. Nice to see some defending those who are supposed to uphold law and order and be beyond reproach. The copper who killed Ian Tomlinson wasn't wearing his number either. If I was to take my number plates off my car and deliberately drive into a person who is slowly walking across the road trying to antagonise me, I'm sure you'd be the 1st on here to defend me too.... Wouldn't you?