If I remember correctly, quite a few people brought placards with cartoons on, despite the organisers backsliding over the issue.
Most of them, just stood silently or remained dignified. I stood next to one of them from Civil Liberty (see here:
www.civilliberty.org.uk) and although the police took lots of pictures and moved closer and closer during the demo, he didn't get nicked.
The individual who did get nicked, if I remember, jumped around like a loon shouting and gesticulating, waving his placard in a crazy fashion. I doubt they are doing him for incitement to whatever, but for a breach of public order.
I hope he behaves himself in court, otherwise no amount of special pleading will save him.