You have to consider the different context at play here; the UK has never had a history of "fundamentalist" (for want of a better word) free speech like there is in the US. There are plenty of laws on the books, from sending malicious communications to inciting racial hatred, that prevent speech that would be entirely legal in the US.
I think that's something that's reflected (either a cause or an effect, I'm not sure which) in public opinion, too; there's certainly no widespread outcry here at these types of arrest. The only recent case I can think of where the ruling was against free speech and where public opinion was significantly against the ruling was the Robin Hood Airport tweet, where someone tweeted an obviously incredible threat to blow up an airport.[2]
[1]: http://www.guardian.co.uk/uk/2012/mar/27/student-jailed-fabr...